We provide dual nature of radiation and matter practice exercises, instructions, and a learning material that allows learners to study outside of the classroom. We focus on dual nature of radiation and matter skills mastery so, below you will get all questions that are also asking in the competition exam beside that classroom.

#### List of dual nature of radiation and matter Questions

Question No | Questions | Class |
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1 | In Millikan’s oil drop experiment an oil drop of radius ( r ) and charge ( Q ) is held in equilibrium between the plates of a charged parallel plate ‘capacitor when the potential difference is ( V . ) To keep a drop of radius ( 2 r ) and with a charge ( 2 Q ) in equilibrium between the plates, the potential difference required will be : A . ( 8 V ) в. ( 4 V ) ( c .2 V ) D. ( 1 V ) |
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2 | Which of the following shows particle nature of light ? A. Refraction B. Interference c. Polarization D. Photoelectric effect |
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3 | Let ( n_{r} ) and ( n_{b} ) be respectively the number of photons emitted by a red bulb and a blue bulb of equal power in a given time, then: A ( cdot n_{r}=n_{b} ) в. ( n_{r}n_{b} ) D. data insufficient |
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4 | If the ( K E ) of a free electron doubles then its de-Broglie wavelength changes by a factor A ( cdot frac{1}{2} ) в. ( frac{1}{sqrt{2}} ) ( c cdot 2 ) D. ( sqrt{2} ) |
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5 | An electron is confined in the region of width ( 1 A^{circ} ). Estimate its K.E. A. 3.4 ev B. 3.8 ev c. 13.6 ev D. 10.2 ev |
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6 | An electric field can just support a water droplet ( 1.0 times 10^{-6} mathrm{m} ) in diameter carrying one electron charge. The magnitude of electric field strength is A ( cdot 3.21 times 10^{4} V / m ) В. ( 2.31 times 10^{4} V / m ) C ( .1 .32 times 10^{4} V / m ) D. ( 6.42 times 10^{4} V / m ) |
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7 | The stopping potential in an experiment of photon is ( 2 mathrm{eV} ). What is the maximum kinetic energy of photoelectrons emitted ? |
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8 | 35. In Q. 32, if the cathode and the anode are kept at the same potential, the emitted electrons have (a) the same KE equal to 1.36 eV (b) the average KE equal to (1.36/2) eV (c) the maximum KE equal to 1.36 eV (d) the minimum KE equal to 1.36 eV |
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9 | The work function of a certain metal is ( 3.31 times 10^{-19} J . ) Then, the maximum kinetic energy of photoelectrons emitted by incident radiation of wavelength 5000 A is ( left(G i v e n h=6.62 times 10^{-34} J-s, c=right. ) ( left.mathbf{3} times mathbf{1 0}^{-mathbf{8}} mathbf{m} s^{-1}, boldsymbol{e}=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{1 9}} boldsymbol{C}right) ) A ( .248 e V ) B. ( 0.41 e V ) c. ( 2.07 e V ) D. ( 0.82 e V ) |
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10 | In which of the following transition will the wavelength be minimum? A ( . n=6 ) to ( n=4 ) в. ( n=4 ) to ( n=2 ) c. ( n=3 ) to ( n=1 ) D. ( n=2 ) to ( n=1 ) |
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11 | If we assume kinetic energy of a proton is equal to energy of the photon, the ratio of de Broglie wave length of proton to photon is proportional to: A. ( E ) ( mathbf{B} cdot E^{-1 / 2} ) ( c cdot E^{1 / 2} ) D. ( E^{3 / 2} ) |
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12 | The minimum energy required to dissociate ( A g B r ) bond in ( 0.6 e V . A ) photographic flim is coated with a sliver bromide layer. Find the maximum wavelength whose signature can be recorded on the film A. ( 207 n m ) в. 702 ( n m ) c. 207 ( A^{circ} ) D. 2070 ( n m ) |
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13 | In photoelectric effect, the photocurrent A. depends both on intensity and frequency of the incident light. B. does not depend on the frequency of incident light but depends on the intensity of the incident light. C. decreases with increase in frequency of incident light. D. increases with increase in frequency of incident light. |
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14 | A charged drop of radius ( 1.92 mathrm{mm} ) is kept stationary by the application of an electric field of ( 1.65 times 10^{6} mathrm{N} / mathrm{C} ) in Millikans oil drop experiment. The charge, if the density of oil is 920 ( K g / m^{3}, ) is A ( cdot 1.72 times 10^{-18} ) В. ( 16.2 times 10^{-19} ) c. ( 1.82 times 10^{-17} ) D. ( 1.92 times 10^{-17} ) |
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15 | The wavelength associated with an electron having kinetic energy is given by the expression: ( mathbf{A} cdot h / sqrt{2 m E} ) в. ( 2 h / m E ) c. ( 2 m h E ) D. ( frac{2 sqrt{2 m E}}{h} ) |
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16 | Write down de Broglie’s relation and explain the terms therein. | 12 |

17 | A body of mass ( x k g ) is moving with velocity of ( 100 m ) sec ( ^{-1} ). Its de Broglie wavelength is ( 6.62 times 10^{-35} ) m. Hence ( x ) is: ( left[boldsymbol{h}=mathbf{6 . 6 2} times mathbf{1 0}^{-mathbf{3 4}} boldsymbol{J}-boldsymbol{s e c}right] ) A. ( 0.25 k g ) B. ( 0.15 k g ) c. ( 0.2 k g ) D. ( 0.1 k g ) |
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18 | U db 15. In an experiment, electrons are made to pass through a narrow slit of width d comparable to their de Broglie wavelengths. They are detected on a screen at a distance D from the slit (see the figure). Which of the following graphs can be expected to represent the number of electrons N detected as a function of the detector position y(y = 0 corresponds to the middle of the slit)? у (a)N + (b) N 47- (C)N+ f d (d) NA |
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19 | Ultra – violet rays are detected by: A. Fluoroscence B. Thermopile C. Thermo – couple D. Thermometer |
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20 | If Bohr radius is ( r_{0}, ) the corresponding de Broglie wavelength of the electron is ( ^{mathbf{A}} cdotleft(frac{2 pi}{r_{o}}right) ) В ( cdotleft(frac{r_{o}}{2 pi}right) ) c. ( left(frac{1}{2 pi r_{o}}right) ) D. ( 2 pi r_{o} ) |
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21 | In an experiment of photoelectric effect, the graph of maximum kinetic energy ( E_{k} ) of the emitted photoelectrons versus the frequency v of the incident light is a straight line ( A B ) as shown in Figure below: (i) Threshold frequency of the metal. (ii) Work function of the metal. (iii) Stopping potential for the photoelectrons emitted by the light of frequency ( boldsymbol{v}=mathbf{3 0 x} times mathbf{1 0}^{mathbf{1 4}} mathbf{H z} ) |
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22 | If in Millikan’s oil drop experiment charges on drops are found to be ( 8 mu C, 12 mu C, 20 mu C, ) then quanta of quanta of charge is :- ( A cdot 8 mu C ) в. ( 4 mu C C ) c. ( 20 mu C ) D. ( 12 mu C ) |
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23 | A photoelectric cell is lightened by a light source, situated at a distance ( d ) from the cell. If distance becomes ( boldsymbol{d} / mathbf{2} ) then number of electrons emitted per sec will be:- A. Remains same B. Four times c. Two times D. One fourth |
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24 | cathode plate inside a vacuum tube as shown in the figure. The work function of the cathode surface is ( phi ) and the anode is a wire mesh of conducting material kept at a distance d from the cathode. A potential difference V is maintained between the electrodes. If the minimum de Broglie wavelength of the electrons passing through the anode is ( lambda_{e}, ) which of the following statement(s) is(are) true? A ( cdot lambda_{e} ) increases at the same rate as ( lambda_{p h} ) for ( lambda_{p h}>phi / e) lambda_{e} ) is pproximately halved if ( V ) is made four time |
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25 | If the wavelength of particle of momentum ( P ) is equal to ( lambda ), then what will be its wavelength for momentum ( mathbf{1 . 5 P ?} ) A ( cdot frac{2}{3} lambda ) в. ( frac{4}{3} lambda ) c. ( frac{3}{2} ) D. ( lambda ) |
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26 | What should be the minimum work function of a metal so that visible light is able to cause emission? (visible light=400-700 ( n m ) ) A .1 .77 eV B. 1.87 ( e V ) c. 1.97 eV D. None of these |
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27 | Light of two different frequencies whose photons have energies leV and ( 2.5 mathrm{eV} ) successively illuminate a metal of work function 0.5 eV.The ratio of the maximum speeds of the emitted electrons will he A .1: 5 B. 1: 4 ( c cdot 1: 2 ) D. 1: |
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28 | 65. A 60 W bulb is placed at a distance of 4 m from you. The bulb is emitting light of wavelength 600 nm uniformly in all directions. In 0.1 s, how many photons enter your eye if the pupil of the eye is having a diameter of 2 mm? [Take hc = 1240 eV-nm] (a) 2.84 x 1012 (b) 2.84 x 1011 (c) 9.37 x 10″ (d) 6.48 x 1011 |
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29 | Monochromatic light of wave length ( 667 mathrm{nm} ) is produced by a helium neon laser. The power emitted is ( 9 mathrm{mW} ). The number of photons arriving per second on the average at a target irradiated by this beam is A ( cdot 3 times 10^{16} ) В . ( 3 times 10^{19} ) ( mathrm{c} cdot 9 times 10^{15} ) D. ( 9 times 10^{17} ) |
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30 | S 16. The surface of a metal is illuminated with a light of wavelength 400 nm. The kinetic energy of the ejected photoelectrons was found to be 1.68 eV. The work function of the metal is (hc = 1240 eV nm) (a) 3.09 eV (b) 1.41 eV (c) 151 eV (d) 1.68 eV (AIEEE 2009) |
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31 | The kinetic energy of an electron get tripled then the de-Broglie wavelength associated with electron changes by a factor of A ( cdot frac{1}{3} ) B. ( sqrt{3} ) c. ( frac{1}{sqrt{3}} ) D. 3 |
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32 | The energy of a ( K ) -electron in tungsten is ( -20 k e V ) and of an ( L ) -electrons is ( -2 k e V . ) The wavelength of ( X ) -rays emitted when there is electronjump from ( boldsymbol{L} ) to ( boldsymbol{K} ) shell: A ( .0 .3443 AA ) в. ( 0.6887 AA ) c. ( 1.3982 dot{A} ) D. 2.78 音 |
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33 | If the shortest wavelength of the continuous X-ray spectrum coming out of a Coolidge tube is ( 0.01 n m ), then the de Broglie wavelength of the electron reaching the target metal in the Coolidge tube is approximately ( left(h c=12400 e V A, h=6.63 times 10^{-34} ) in right. MKS, mass of electron= ( 9.1 times ) ( left.10^{-31} k gright) ) A . 0.35 в. 0.035 ( c .35 ) D. 1350 |
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34 | The threshold frequency for a photosensitive metal is ( 3.3 times 10^{14} H z . ) If light of frequency ( 8.2 times 10^{14} H z ) is incident on this metal, the cutoff voltage for the photoelectric emission is nearly: A . ( 1 v ) B. 2V c. ( 3 v ) D. ( 5 v ) |
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35 | Define the term work function of a metal. |
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36 | Assertion There is a physical significance of matter waves. Reason Both interference and diffraction occurs in it. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion. B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion. C. Assertion is correct but Reason is incorrect. D. Both Assertion and Reason are incorrect. |
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37 | 17. If the momentum of an electron is changed by Ap, then the de-Broglie wavelength associated with it changes by 0.50%. The initial momentum of the electron will be 4 (a) (6) Ap 200 (c) 1994p 199 (d) 400 Ap |
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38 | Work function of sodium is ( 2.3 e V ). Does sodium show photo-electric emission for light wavelength 6800 A? |
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39 | A proton and an electron initially at rest are accelerated by the same potential difference. Assuming that a proton is 2000 times heavier than an electron, what will be the relation between the de Broglie wavelength of the proton ( left(boldsymbol{lambda}_{boldsymbol{p}}right) ) and that of electron ( left(boldsymbol{lambda}_{e}right) ) ? A ( cdot lambda_{p}=2000 lambda_{e} ) B. ( lambda_{p}=frac{lambda_{e}}{2000} ) c. ( lambda_{p}=20 sqrt{5 lambda_{e}} ) D. ( lambda_{p}=frac{lambda_{e}}{20 sqrt{5}} ) |
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40 | The work function of a substance is 4.0eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately A . ( 5400 A^{circ} ) в. ( 4000 A^{circ} ) c. ( 3100 A^{circ} ) D. 2200A ( ^{text {0 }} ) |
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41 | 39. Silver has a work function of 4.7 eV. When ultraviolet lich of wavelength 100 mm is incident upon it, a potential 7.7 V is required to stop the photoelectrons from reaching the collector plate. How much potential will be required to stop the photoelectrons when light of wavelength 2001 mm is incident upon silver? (a) 1.5 V (b) 3.85 V (c) 2.35 V (d) 15.4 V |
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42 | Relation between wavelength of photon and electron of same energy is ( mathbf{A} cdot lambda_{p h}>lambda_{e} ) ( mathbf{B} cdot lambda_{p h}<lambda_{e} ) ( mathbf{c} cdot lambda_{p h}=lambda_{e} ) D. ( frac{lambda_{c}}{lambda_{p h}}= ) constant |
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43 | 47. In Q. 46, the work function is (a) 0.212 eV (b) 0.313 eV (c) 0.414 eV (d) 0.515 eV 40 TL |
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44 | Light of wavelength ( lambda ), strikes a photoelectric surface and electrons are ejected with an energy E. If E is to be increased to exactly twice its original value, the wavelength changes to ( lambda^{prime} ) where A ( cdot x^{prime} ) is less than ( frac{lambda}{2} ) B. ( lambda^{prime} ) is greater than ( frac{lambda}{2} ) c. ( lambda^{prime} ) is greater than ( frac{lambda}{2} ) but less than ( lambda ) ( lambda^{prime} lambda^{prime} ) is exactly equal to ( frac{lambda}{2} ) |
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45 | A graph is plotted between uncertainty in position and inverse of uncertainty in wavelength for an electron. We get a straight line passing through the origin. Calculate voltage through which electron is accelerated with A. ( 150 mathrm{v} ) B. 75 V c. 37.5 D. 300 |
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46 | 8. If the kinetic energy of a free electron doubles, its de Broglie wavelength changes by the factor (a) (b) 5 (c) 2 (AIEEE 2005) |
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47 | Calculate the velocity of an electron having wavelength of ( 0.15 n m . ) Mass of an electron is: ( 9.109 times 10^{-28} g ) ( left(h=6.626 times 10^{-27} e r g-sright) ) A ( cdot 2.062 times 10^{-8} mathrm{cms}^{-1} ) B. ( 2.062 times 10^{15} mathrm{cms}^{-1} ) c. ( 2.062 times 10^{10} mathrm{cms}^{-1} ) D. ( 4.84 times 10^{8} mathrm{cms}^{-1} ) |
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48 | A water drop of radius ( 10^{-6} mathrm{m} ) is charged with one electron. The electric field required to keep it stationary is (given density of water ( boldsymbol{rho}= ) ( mathbf{1 0 0 0 k g} / boldsymbol{m}^{3} ; boldsymbol{g}=mathbf{9 . 8 m} / boldsymbol{s}^{2} ) A ( .2 .566 times 10^{5} V / m ) B . ( 1.283 times 10^{5} mathrm{V} / mathrm{m} ) c. ( 3.849 times 10^{5} mathrm{V} / mathrm{m} ) D. ( 5.132 times 10^{5} mathrm{V} / mathrm{m} ) |
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49 | With the decrease in the wave length of the incident radiation the velocity of the photoelectrons emitted from a given metal A. Remains same B. Increases c. Decreases D. Increases first and then decreases |
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50 | Define the following: Threshold frequency and work function. |
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51 | Light rays of wavelengths ( 6000 A ) and of photon intensity 39.6 watts ( / m^{2} ) incidents on a metal surface. If only ( 1 % ) of photons incident on the surface emit photoelectrons, then the number of electrons emitted per second per unit area from the surface will be approximately: [Planck constant ( boldsymbol{h}=mathbf{6 . 6 4} times mathbf{1 0}^{-mathbf{3 4} mathbf{J}} boldsymbol{s} ) Velocity of light ( left.=mathbf{3} times mathbf{1 0}^{mathbf{8}} boldsymbol{m} boldsymbol{s}^{-mathbf{1}}right] ) A ( cdot 12 times 10^{18} ) В. ( 10 times 10^{18} ) C ( .12 times 10^{17} ) D. ( 12 times 10^{15} ) |
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52 | A homogeneous ball (mass ( =boldsymbol{m} ) ) of ideal black material at rest is illuminated with a radiation having a set of photons (wavelength ( =lambda ) ), each with the same momentum and the same energy. The rate at which photons fall on the ball is n. The linear acceleration of the ball is: ( A cdot m lambda / n h ) B. ( n h / m lambda ) c. ( n h /(2 pi)(m lambda) ) D. ( 2 p m lambda / n h ) |
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53 | 53. Light of wavelength 0.6 um from a sodium lamp falls on a photocell and causes the emission of photoelectrons for which the stopping potential is 0.5 V. With light of wavelength 0.4 um from a mercury vapor lamp, the stopping potential is 1.5 V. Then, the work function (in electron volts] of the photocell surface is (a) 0.75 eV (b) 1.5 eV (c) 3 eV (d) 2.5 eV |
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54 | The de-Broglie wavelength of a proton ( left(text {mass}=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{2 7}} mathbf{k g}right) ) accelerated through a potential difference of ( 1 mathrm{kV} ) is : B . ( 0.9 times 10^{-12} mathrm{m} ) ( c .7 dot{h} ) D. ( 0.9 times 10^{-19} n m ) |
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55 | If the de-Broglie wavelength of a particle of mass ( m ) is 100 times its velocity then its value in terms of its mass ( (m) ) and Planck’s constant ( (boldsymbol{h}) ) is: A ( cdot frac{1}{10} sqrt{frac{m}{h}} ) в. ( 10 sqrt{frac{h}{m}} ) ( c cdot frac{1}{10} sqrt{frac{h}{m}} ) D. ( 10 sqrt{frac{m}{h}} ) |
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56 | Work function is A. energy necessary to eject the electron from its orbit B. energy necessary to eject an electron from within a metal body C. minimum necessary energy to eject an electron from a metal surface D. wavelength necessary for releasing an electron from a body |
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57 | 73. As energy associated with changes with its wavelength, often the reciprocal of the wavelength 1/2. is used to describe energy associated with that wavelength. Then, mark the correct equivalence. (a) 1 eV = 5092.6 cm- and 1 cm-‘ = 1.2398 x 10-4 eV (b) 1 eV = 1239.8 cm- and 1 cm-‘ = 8068 x 10-7eV (c) 1 eV = 8068.8 cm-‘ and 1 cm-‘ = 6.65 x 10-19 eV (d) 1eV=8065 x 10 cm and 1 cm’=1.2398 x 10 *eV |
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58 | 61. A monochromatic source of light is placed at a large distance d from a metal surface. Photoelectrons are ejected at rate n, the kinetic energy being E. If the source is brought nearer to distance d/2, the rate and kinetic energy per photoelectron become nearly (a) 2n and 2E (b) 4n and 4E (c) 4n and E (d) n and 4E |
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59 | When a photon of energy ( 7 e V ) is made incident on a metal then the emitted electron is stopped by a stopping potential of ( -5.5 V . ) The work function of metal will be : A. ( -1.5 e V ) B. ( 1.5 e V ) c. ( 12.5 e V ) D. ( 37.5 e V ) |
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60 | If ( 10,000 V ) are applied across an ( X ) -ray tube, find the ratio of wavelength of the incident electrons and the shortest wavelength of ( X ) -ray coming out of the X-ray tube, given ( e / m ) of electron ( = ) ( 1.8 times 10^{11} C k g^{-1} ) ( mathbf{A} cdot 1: 10 ) B. 10: 1 c. 5: 1 D. 1: 5 |
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61 | 10 18. If a source of power 4 kW produces 1020 photons per second, the radiation belongs to a part of the spectrum called (a) X-rays (b) ultraviolet rays (c) microwaves (8) Witays aves ) yltraviolet raya IEEE 2010 |
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62 | 63. All electrons ejected from a surface by incident light of wavelength 200 nm can be stopped before traveling 1 m in the direction of a uniform electric field of 4 NC-. The work function of the surface is (a) 4 eV (b) 6.2 eV (c) 2 eV (d) 2.2 eV |
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63 | A free particle with initial kinetic energy ( mathrm{E} ) and de-broglie wavelength ( lambda ) enters a region in which it has potential energy U. What is the particle’s new de- Broglie wavelength? A ( cdot lambda(1-U / E)^{-1 / 2} ) в. ( lambda(1-U / E) ) c. ( lambda(1-U / E)^{-1} ) D. ( lambda(1-U / E)^{1 / 2} ) |
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64 | A surface has work function ( 3.3 e V ) Which of the following will cause emission? A. ( 100 W ) incandascent lamp B. 40 ( W ) flouroscent lamp c. ( 20 W ) sodium lamp D. 20 ( W ) Hg lamp |
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65 | 16. Radiation pressure on any surface (a) is dependent on wavelength of the light used (b) is dependent on nature of surface and intensity of light used (c) is dependent on frequency and nature of surface (d) depends on the nature of source from which light is coming and on nature of surface on which it is falling |
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66 | An ( alpha ) -particle and a proton are accelerated from rest by a potential difference of ( 100 V . ) After this, their de Broglie wavelengths are ( lambda_{alpha} ) and ( lambda_{p} ) respectively. The ratio ( lambda_{p} / lambda_{alpha}, ) to the nearest integer, is: |
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67 | The photons from Blamer series in hydrogen spectrum having wavelength between ( 450 mathrm{nm} ) to ( 700 mathrm{nm} ) are incident on a metal surface of work function 2 eV. Find the maximum kinetic energy of one photo electron. |
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68 | An ( alpha- ) particle and a proton have their masses in the ratio 4: 1 and charges in the ratio ( 2: 1 . ) Find ratio of their de- Broglie wavelengths when both move with equal velocities. ( mathbf{A} cdot 1: 4 ) B. 4: 1 c. 1: 2 ( D cdot 2: 1 ) |
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69 | 11. The time by a photoelectron to come out after the photon strikes is approximately (a) 10-‘s (b) 1045 (c) 10-10 s (d) 10-16S (AIEEE 2006) |
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70 | In Millikan’s oil drop experiment, an oil drop of density 8 times of air is held stationary by applying a field E. The field required to hold another drop of same radius and carrying same charge but density is 22 times the density of air is ( A cdot E ) B . 2E c. зЕ D. 4E |
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71 | In hydrogen spectrum, the wavelength of the line is ( 656 mathrm{nm} ), where as in the spectrum of a distant galaxy, the line wavelength is ( 706 mathrm{nm} ). Estimated speed of galaxy with respect to the earth is : A ( cdot 2 times 10^{8} m / s ) В. ( 2 times 10^{7} m / s ) c. ( 2 times 10^{6} mathrm{m} / mathrm{s} ) D. ( 2 times 10^{5} mathrm{m} / mathrm{s} ) |
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72 | If ( 5 % ) of the energy supplied to a bulb is radiated as visible light, the number of visible quanta emitted per second by a 100W bullb, assuming the wavelength of visible light to be ( 5.6 times 10^{-5} mathrm{cm}, ) is A. ( 1.4 times 10^{19} ) B . ( 1.4 times 10^{20} ) ( mathrm{c} cdot 2 times 10^{19} ) D. ( 2 times 10^{20} ) |
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73 | The energy that should be added to an electron to reduce its de-Broglie wavelength from 1 nm to 0.5 nm is. A. Four times the initial energy B. Equal to the initial energy c. Twice the initial energy D. Thrice the initial energy |
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74 | An electronic transition from ( M ) shell ( =3 ) to ( K ) shell ( (n=1) ) takes place in a hydrogenatom. Find the wavelength of radiation emited. ( left(R=109,677 mathrm{cm}^{-1}right) ) A ( cdot 1026 A^{circ} ) ( ^{circ} ) B . ( 1.026 times 10^{-5} mathrm{m} ) c. ( 1.026 times 10^{-3} mathrm{cm} ) D. none of these |
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75 | Two electrons are moving with nonrelativistic speeds perpendicular to each other. If corresponding de Broglie wavelengths are ( lambda_{1} ) and ( lambda_{2}, ) their de Broglie wavelength in the frame of reference attached to their centre of mass is: ( mathbf{A} cdot lambda_{C M}=lambda_{1}=lambda_{2} ) ( ^{mathrm{B}} cdot frac{1}{lambda_{C M}}=frac{1}{lambda_{1}}+frac{1}{lambda_{2}} ) ( ^{mathbf{C}} lambda_{C M}=frac{2 lambda_{1} lambda_{2}}{sqrt{lambda_{1}^{2}+lambda_{2}^{2}}} ) ( lambda_{C M}=left(frac{lambda_{1}+lambda_{2}}{2}right) ) |
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76 | Radiations of two photon’s energy, twice and ten times the work function of metal are incident on the metal surface successively. The ratio of maximum velocities of photoelectrons emitted in two cases is: A . 1: 2 B. 1:3 ( c cdot 1: 4 ) D. 1: |
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77 | Assume that a molecule is moving with the root mean square speed at temperature ( 300 mathrm{K} ). The de Broglie wavelength of nitrogen molecule is (Atomic mass of nitrogen ( =14.0076 mathrm{u}, mathrm{h} ) ( =mathbf{6 . 6 3} times mathbf{1 0}^{-mathbf{2 7}} boldsymbol{J} boldsymbol{s}, boldsymbol{k}_{boldsymbol{B}}=mathbf{1 . 3 8} times ) ( mathbf{1 0}^{-mathbf{2 3}} boldsymbol{J} boldsymbol{K}^{-mathbf{1}}, mathbf{1} boldsymbol{u}=mathbf{1 . 6 6} cdot times mathbf{1 0}^{-mathbf{2 7}} boldsymbol{k} boldsymbol{g} ) ( mathbf{A} cdot 2.75 times 10^{-11} m ) В. ( 2.75 times 10^{-12} m ) c. ( 3.24 times 10^{-11} mathrm{m} ) D. ( 3.24 times 10^{-12} mathrm{m} ) |
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78 | Which metal(s) can be used to produce electrons by the photoelectric effect from given source of light? A. Barium only B. Barium or lithium c. Lithium, tantalum or tungsten D. Tungsten or tantalum |
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79 | The electric field of certain radiation is given by the equation ( boldsymbol{E}= ) ( 200left[sin left(4 pi times 10^{10}right) t+sin (4 pi xright. ) ( left.left.mathbf{1 0}^{mathbf{1 5}}right) boldsymbol{t}right] ) falls in a metal surface having work function ( 2.0 e V . ) The maximum kinetic energy ( in eV) of the photoelectrons is [use Planck’s constant ( (h)=6.63 times 10^{-34} J-s ) and electron charge ( left(boldsymbol{E}=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{1 9}} boldsymbol{C}right) ) A. 3.3 B. 4.3 c. 5.3 D. 6.3 E. 7.3 |
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80 | A charged oil drop is suspended in uniform field of ( 3 times 10^{4} V / m ) so that it neither falls nor rises. The charge on the drop will be: (take the mass of the charge ( =mathbf{9 . 9} times mathbf{1 0}^{-15} mathbf{k g} ) and ( mathbf{g}= ) ( left.10 m / s^{2}right) ) A . ( 3.3 times 10^{-18} mathrm{C} ) в. ( 3.2 times 10^{-18} mathrm{C} ) c. ( 1.6 times 10^{-18} mathrm{C} ) D. ( 4.8 times 10^{-18} mathrm{C} ) |
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81 | The de Broglie wavelength of electron accelerated through ( V ) volt is nearly given by: ( underset{(i n A)}{lambda}=left[frac{x}{V}right]^{1 / 2} . ) Find the value of ( frac{x}{75} ) |
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82 | 7. A material particle with a rest mass m, is moving with a velocity of light c. Then, the wavelength of the de Broglie wave associated with it is (a) (hlm.c) (b) zero (c) (d) (m.clh) |
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83 | To increase de-Broglie wavelength of an electron from ( 0.5 times 10^{-10} mathrm{m} ) to ( 10^{-10} mathrm{m} ) its energy should be A. Increased to 4 times B. Halvedd c. Doubled D. Decreases to fourth parttt |
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84 | Radiation, with wavelength ( 6561 A ) falls on a metal surface to produce photoelectrons. The electrons are made to enter a uniform magnetic field of ( 3 times ) ( 10^{-4} mathrm{T} . ) If the radius of the largest circular path followed by the electrons is ( 10 mathrm{mm} ), the work function of the metal is close to? A ( .0 .8 mathrm{eV} ) B. ( 1.1 mathrm{eV} ) c. 1.6 ev D. 1.8 ev |
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85 | Identify the reason why an observer cannot detect the wave nature of a fast moving truck. A. The momentum of the truck is too large B. The velocity of the wave is too large c. There are no waves to be detected D. The frequency is too low E. The wavelengths are too small |
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86 | de Broglie relation is true for A. All particles B. Charged particles only c. Negatively charged particles only D. Massless particles like photons only |
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87 | A body of mass ( 100 g ) moves at the speed of ( 36 k m / h ). The de-Broglie wavelength related to it is of the order ( boldsymbol{m} ) ( left(h=6.626 times 10^{-34} J sright) ) A ( cdot 10^{-24} ) B . ( 10^{-14} ) c. ( 10^{-34} ) the ( 4^{-34} 4 ) D. ( 10^{-44} ) |
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88 | ( frac{L}{L} ) | 12 |

89 | The electron microscope is based on the principle of A. photoelectric effect B. particle nature of electrons c. particle nature of electron D. dual nature of matter |
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90 | What determines the intensity of light in the photon picture of light? | 12 |

91 | 29. The frequency of incident light falling on a photose metal plate is doubled, the KE of the emitted photoelectrons is (a) double the earlier value (b) unchanged (c) more than doubled (d) less than doubled tome buye |
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92 | Illuminating the surface of a certain metal alternately with light of wavelength ( lambda_{2}=0.54 mu m ) and ( lambda_{2}= ) ( 0.54 mu m, ) it was found that the corresponding maximum velocities of photo electrons have a ratio ( eta=2, ) Find the work function of that metal. A ( .6 .99 e V ) B. ( 1.9 e V ) c. ( 7.53 e V ) D. ( 1.88 e V ) |
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93 | A monochromatic source of light operating at ( 200 mathrm{W} ) emits ( 4 times 10^{20} ) photons per second. Find the wavelength of light. A . 400 nm B. 200nm C ( .4 times 10^{-10} dot{A} ) D. None of these |
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94 | An oil drop of 10 excess electrons is held stationary under a constant electric field of ( 3.65 times 10^{4} N C^{-1} ) in Millikan’s oil drop experiment. The density of oil is ( 1.26 g c m^{-3} . ) Radius of the oil drop is (Take ( left.g=9.8 m s^{-2}, e=1.6 times 10^{-19} Cright) ) A ( cdot 1.04 times 10^{-6} mathrm{m} ) в. ( 4.8 times 10^{-5} mathrm{m} ) ( mathbf{c} cdot 4.8 times 10^{-18} m ) D. ( 1.13 times 10^{-18} mathrm{m} ) |
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95 | 55. Monochromatic light incident on a metal surface emits electrons with kinetic energies from zero to 2.6 eV. What is the least energy of the incident photon if the tightly bound electron needs 4.2 eV to remove? (a) 1.6 eV (b) From 1.6 eV to 6.8 eV (c) 6.8 eV (d) More than 6.8 eV |
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96 | 34. In Q. 32, if the intensity of light is made 410, then the saturation current will become (a) 0.40 x 1 ua (b) 0.40 x 2 ua (c) 0.40 x 4 uA (d) 0.40 x 8 UA |
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97 | The surface of a metal is illuminated with the light of 400 nm. The kinetic energy of the ejected photoelectrons was found to be ( 1.68 mathrm{eV} ). The work function of the metal is : ( (h c=1240 mathrm{eV} . n m) ) A . ( 3.09 mathrm{eV} ) в. ( 1.41 mathrm{eV} ) c. ( 1.51 mathrm{eV} ) D. ( 1.68 mathrm{eV} ) |
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98 | An oil drop of radius r carrying a charge q’ remains stationary in the presence of electric field of intensity E. If the density of oil is ( rho, ) then ( ^{mathbf{A}} cdot E=frac{4}{3} pi r^{3} rho g q ) B. ( quad E=frac{4}{3} pi r^{3} rho g ) c. ( _{E}=frac{4}{3} pi r^{3} rho g / q ) D. ( E=frac{4}{3} pi r^{3} rho / g^{3} ) |
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99 | Davisson and Germer experiment represents nature of the electron. A. Wave B. Particle c. wave and particle D. Doesn’t represent any nature |
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100 | The work function of cesium metal is 2eV. It means that A. The energy necessary to emit electrons from metal surface is ( 2 mathrm{eV} ) B. The energy of electrons emitted from metallic surface is ( 2 e v ) C. The value of photoelectric current is ( 2 mathrm{eV} ) D. The value of threshold frequency is ( 2 e v ) |
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101 | The minimum amount of energy required to emit an electron from a metal surface is called A. Force function B. Power function c. work function D. None of the above |
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102 | An isolated metal body is illuminated with monochromatic light and is observed to becomes charged to a steady positive potential ( 1.0 mathrm{V} ) with respects to the surrounding. the work function of the metal is ( 3.0 mathrm{eV} ). The frequency of the incident light is |
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103 | The surface of some material is radiated in turn by waves of ( lambda=3.5 times ) ( 10^{-7} ) and ( lambda=5.4 times 10^{-7} m ) respectively The ratio of the stopping potential in the two cases in ( 2: 1 . ) The work function of the metal is: A . ( 1.05 e V ) B. ( 1.5 e V ) c. ( 2.05 e V ) D. ( 2.5 e V ) |
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104 | Find the frequency of light which ejects electrons from a metal surface, fully stopped by a retarding potential of ( 3.3 V ) If photo electric emission begins in this metal at a frequency of ( 8 times 10^{14} mathrm{Hz} ) calculate the work function (in eV) for this metal. |
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105 | Work function is the energy required A. To excite an atom B. To produce X-rays C. To eject an electron just out of the surface D. To explode the atom |
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106 | A proton is accelerated to ( 225 V ). Its deBroglie wavelength is: ( mathbf{A} cdot 0.0019 n m ) B. ( 0.02 n m ) c. ( 0.003 n m ) D. ( 0.4 n m ) |
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107 | 12. Find the ratio of de Broglie wavelength of a proton and an d-particle which have been accelerated through sam potential difference. (a) 2V2:1 (b) 3:2 (c) 3√2:1 (d) 2:1 |
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108 | In Millikan’s experiment, the slope of ( v ) versus ( V_{o} ) graph was found to be ( 4.125 times 10^{-15} V s . ) Given ( e=1.6 times ) ( 10^{-19} C, ) the value of Planck’s constant is B. ( 6.4 times 10^{-34} J s ) C ( .4 .125 times 10^{-34} mathrm{Js} ) D. ( 6.6 times 10^{-34} J s ) |
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109 | The direction of the electric field in Millikan’s oil drop experiments acts. A. Downwards B. Upwards c. First upwards then downwards D. First downwards, then upwards |
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110 | 13. Electrons accelerated by potential V are diffracted from a crystal. If d = 1 Å and i = 30°, V should be about (h=6.6 x 10-34 Js, me = 9.1 x 10-kg, e = 1.6 x 10-19 C) (a) 500 V (b) 1000 V (c) 2000 V (d) 50 V 1.cc |
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111 | 70. A silver ball of radius 4.8 cm is suspended by a thread in the vacuum chamber. UV light of wavelength 200 nm is incident on the ball for some times during which a total energy of 1 x 10-‘J falls on the surface. Assuming on an average one out of 10 photons incident is able to eject electron. The potential on sphere will be (a) 1V (c) 3V (d) Zero (b) 2 V |
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112 | Find the frequency of 1 MeV photon. Given wavelength of a ( 1 mathrm{keV} ) photon is ( 1.24 times 10^{-9} m ) Hint: ( boldsymbol{E}=boldsymbol{h} boldsymbol{nu} ) |
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113 | The photo electric work function for a metal surface is 4.125 eV. The cut-off wavelength for this surface A ( cdot 4125 ~ A^{circ} ) B. 2062.5 ( A^{circ} ) c. ( 3000 A^{circ} ) D. 6000A ( ^{text {о }} ) |
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114 | A ( 200 g ) cricket ball is thrown with a speed of ( 3.0 times 10^{3} mathrm{cm} ) sec ( ^{-1} ). What will be its de Broglie’s wavelength? ( left(h=6.6 times 10^{-27} g c m^{2} s e c^{-1}right) ) ( mathbf{A} cdot 1.1 times 10^{-32} c m ) B . ( 2.2 times 10^{-32} mathrm{cm} ) C ( .0 .55 times 10^{-32} mathrm{cm} ) D. ( 11.0 times 10^{-32} mathrm{cm} ) |
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115 | The de-Broglie wavelength associated with a proton changes by ( 0.25 % ) if its momentum is changed by ( P_{o} ). The initial momentum of proton is A ( cdot 100 P_{o} ) в. ( 400 P_{o} ) ( c cdot P_{o} / 400 ) D. ( P_{o} ) |
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116 | Find energy of photon of wavelength ( mathbf{4 0 0 0} stackrel{boldsymbol{o}}{boldsymbol{A}} ) | 12 |

117 | In the following diagram if ( V_{2}>V_{1} ) then ( mathbf{A} cdot lambda_{1}=sqrt{lambda_{2}} ) B ( cdot lambda_{1}lambda_{2} ) |
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118 | Momentum of a photon of wavelength ( lambda ) is: ( A cdot h / lambda ) B. Zero c. ( h lambda / c^{2} ) D. ( h lambda / c ) |
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119 | The photoelectric threshold of a certain metal is 3000 A. If the radiation of ( 2000 A ) is incident on the metal A. electrons will be emitted B. positrons will be emitted c. protons will be emitted D. electrons will not be emitted |
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120 | The wavelength of a certain electron transition in the hydrogen spectrum is 4864 A. Identify the transition. A. Third line Balmer B. First line Lyman c. First line Paschen D. second line Balmer |
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121 | A particle of mass ( mathrm{M} ) at rest decays into particles of masses ( m_{1} ) and ( m_{2} ) having non -zero velocities. The ratio of the de broglie wavelengths of the particles ( lambda_{1} / lambda_{2} ) is : ( mathbf{A} cdot m_{1} / m_{2} ) в. ( m_{2} / m_{1} ) ( c ) D. m1.m2 |
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122 | A microscope using suitable photons is employed to locate an electron in an atom within a distance of 0.1 A. The uncertainty of its velocity is A. ( 5.79 times 10^{5} mathrm{ms}^{-1} ) B. ( 8.79 times 10^{5} mathrm{ms}^{-1} ) C. ( 5.79 times 10^{4} mathrm{ms}^{-1} ) D. ( 3.79 times 10^{5} mathrm{ms}^{-1} ) |
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123 | The de Broglie wavelength ( (lambda) ) associated with a photoelectron varies with the frequency ( ( v ) ) of the incident radiation as, ( left[v_{0} text { is thrshold frequency }right] ) A ( cdot lambda propto frac{1}{left(v-v_{0}right)^{frac{3}{2}}} ) B. ( lambda propto frac{1}{left(v-v_{0}right)^{frac{1}{2}}} ) c. ( a lambda propto frac{1}{left(v-v_{0}right)^{frac{1}{4}}} ) D. ( lambda propto frac{1}{left(v-v_{0}right)} ) |
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124 | Q Type your question- Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electron waves reflected from the planes of atoms in a crystal interfere constructively (see figure). Electrons accelerated by potential Vare diffracted from a crystal. If ( boldsymbol{d}=mathbf{1} boldsymbol{A}^{boldsymbol{o}} ) and ( i=30^{circ}, V ) should be about : ( left(h=6.6 times 10^{-34} j s, m=9.1 timesright. ) ( mathbf{1 0}^{-mathbf{3 1}} mathbf{k g}, e=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{1 9}} mathbf{c} ) A . 2000 v B. ( 50 v ) c. 500 v D. ( 1000 mathrm{v} ) |
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125 | Light of two different frequencies whose photos have energies leV and 2.5eV respectively illuminate a metallic surface whose work function is ( 0.5 e v ) successively. Ratio of maximum speeds of emissions will be ( A cdot 1: 4 ) B. 1: ( c cdot 1: ) D. 1: |
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126 | In Hertz’s experiment the of the electromagnetic waves is equal to the kinetic energy of the charges oscillating between two spheres. A. Frequency B. Energy c. wavelength D. Velocity |
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127 | 10. The potential difference applied to an X-ray tube is v The ratio of the de Broglie wavelength of electron to the minimum wavelength of X-ray is directly proportional to (a) V (b) VV (d) y7/2 (c) 1312 |
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128 | The de Broglie wavelength of an electron in a metal at ( 27^{circ} mathrm{C} ) is ( left(text {Given } boldsymbol{m}_{e}=right. ) ( mathbf{9 . 1} times mathbf{1 0}^{-mathbf{3 1}} mathbf{k g}, boldsymbol{k}_{boldsymbol{B}}=mathbf{1 . 3 8} times ) ( left.10^{-23} J K^{-1}right) ) A ( cdot 6.2 times 10^{-9} mathrm{m} ) В. ( 6.2 times 10^{-10} mathrm{m} ) ( mathbf{c} cdot 6.2 times 10^{-8} m ) D. ( 6.2 times 10^{-7} m ) |
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129 | A proton, a neutron, an electron and an ( alpha ) -particle have same energy. Then their de Broglie wavelengths compare as: ( mathbf{A} cdot lambda_{p}=lambda_{n}>lambda_{e}>lambda_{alpha} ) B . ( lambda_{alpha}<lambda_{p}=lambda_{n}<lambda_{e} ) ( mathbf{c} cdot lambda_{e}lambda_{alpha} ) ( mathbf{D} cdot lambda_{e}=lambda_{p}=lambda_{n}=lambda_{alpha} ) |
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130 | The de Broglie wavelength of an electron moving with a velocity of ( 1.5 times ) ( 10^{8} m s^{-1} ) is equal to that of a photon. Find the ratio of the kinetic energy of the photon to that of the electron. |
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131 | The energy of a neutron in eV whose de- Broglie wavelength is ( 1 mathrm{A} ) A ( cdot 1.67 times 10^{-22} z V ) В. ( 8.13 times 10^{-2} mathrm{eV} ) c. ( 6.62 times 10^{-22} e V ) D. ( 3.23 times 10^{-2} mathrm{eV} ) |
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132 | ( frac{sqrt{2}}{frac{1}{n}} ) | 12 |

133 | The de Broglie wavelength of an electron having 80 eV of energy is nearly ( left(1 e V=1.6 times 10^{-19} J, ) Mass of electron right. ( =9 times 10^{-31} k g ) Planck’s constant ( =mathbf{6 . 6} times mathbf{1 0}^{-mathbf{3 4}} mathbf{J s} ) (nearly) A . ( 140 A^{circ} ) B. 0.14 ( A^{0} ) ( mathbf{c} cdot 14 A^{0} ) D. 1.4 ( A^{0} ) |
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134 | The electron with The electron with de Broglie wavelength ( lambda ) is bombarded on a metal target. Found that photons are emitted through de Broglie wavelength. |
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135 | A radiation is incident on a metal surface of work function ( 2.3 e V ). The wavelength of incident radiation is 600 nm. If the total energy of incident radiation is ( 23 J ), then the number of photoelectrons is A. zero B ( cdot>10^{4} ) ( mathbf{c} cdot=10^{4} ) D. None of these |
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136 | The de-Broglie wavelength of a proton accelerated by ( 400 mathrm{V} ) is A ( .0 .005 AA ) B . 1.0528 , c. ( 0.0568 dot{A} ) D. ( 0.0143 dot{A} ) |
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137 | The work function of a metal in ( 4 e V . ) For the emission of photoelectrons of zero velocity from the metal surface, the wavelength of the incident radiation should be ( mathbf{A} cdot 1700 hat{A} ) в. 2700 А ( c cdot 3100 hat{A} ) D ( cdot 5900 ), |
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138 | A monochromatic source of light operating at ( 200 mathrm{W} ) emits ( 4 times 10^{20} ) photons per second. Find the wavelength of the light ( left(i n times 10^{-7} mright) ) |
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139 | What is the de Broglie wavelength of the electron accelerated through a potential difference of 100 Volt? A ( . ) १२.२७ ( AA ) в. 1.227 , c. 0.1227 , D. 0.001227 ( dot{A} ) |
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140 | Identify the statement which best define the uncertainty principle? A. We cannot know for certain when any given radioactive particle will undergo decay B. We cannot know both the momentum and the position of a particle at the same time c. The laws of physics are the same in all intertial reference frames D. Light exhibits both wave and particle properties E. An unobserved particle can be in two places at the same time |
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141 | The ratio of energy of photon of ( lambda=2000 ) ( A^{o} ) to that of ( lambda=4000 A^{o} ) is : ( A cdot 2 ) B. 1/4 ( c cdot 4 ) D. ( 1 / 2 ) |
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142 | A proton and ( alpha ) -particle are accelerated through the same potential difference. The ratio of their de-Broglie wavelength will be A .1: B. 1: 2 ( c cdot 2: ) D. ( 2 sqrt{2}: 1 ) |
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143 | A charged oil drop falls with terminal velocity ( v_{0} ) in the absence of electric field. An electric field E keeps it stationary. The drop acquires additonal charge ( q ) and starts moving upwards with velocity ( v_{0} . ) The initial charge on the drop was ( A cdot 4 q ) B. 2a ( c cdot q ) D. ( frac{q}{2} ) |
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144 | Electrons with de Broglie wavelength ( lambda ) are bombarded on a metal target. It is found that photons are emitted from the metal target. The minimum wavelength of emitted photons is ( [mathrm{m}= ) mass of eletron] | 12 |

145 | State de Broglie hypothesis. | 12 |

146 | The wavelength associated with a photon of energy 3.31 eV is nearly A. ( 4000 A^{circ} ) B. 3750 ( A^{circ} ) C ( .5000 A^{circ} ) D. 400 A ( ^{text {о }} ) |
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147 | The surface of the metal is illuminated with the light of 400 nm. The kinetic energy of the ejected photoelectrons was found to be ( 1.68 mathrm{eV} ), the work function of metal is : A . ( 1.51 mathrm{eV} ) B. 1.42 ev c. 3.0 ev D. 1.68 ev |
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148 | Photons of energy 7 e ( V ) are incident on two metals ( A ) and ( B ) with work functions ( 6 mathrm{eV} ) and ( 3 mathrm{eV} ) respectively. The minimum de Broglie wavelengths of the emitted photoelectrons with maximum energies are ( lambda_{A} ) and ( lambda_{B}, ) respectively where ( boldsymbol{lambda}_{boldsymbol{A}} / boldsymbol{lambda}_{boldsymbol{B}} ) is nearly: A. 0.5 B. 1.4 ( c cdot 4.0 ) D. 2.0 |
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149 | The de-Broglie wavelength of electron in second Bohr’s orbit is equal to A. circumference of the orbit B. half the circumference of the orbitt c. twice the circumference of the orbit D. four times circumference of the orbit |
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150 | Assertion Mass of moving photon varies inversely as the wavelength. Reason Energy of the particle ( = ) Mass ( times ) (speed of light) ( ^{2} ) A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. If Assertion is incorrect but Reason is correct |
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151 | 30. Lights of two different frequencies whose photons have energies 1 and 2.5 eV, respectively, successively illuminate a metal whose work function is 0.5 eV. The ratio of the maximum speeds of the emitted electrons will be (a) 1:5 (b) 1:4 (c) 1:2 (d) 1:1 launted through potential difference At |
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152 | ILLUSTRATION 28.9 Will photoelectrons be emitted from copper surface, of work function 4.4 eV, when illuminated by a visible light? |
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153 | The force on a hemisphere of radius 1 ( mathrm{cm} ) if a parallel beam of monochromatic light of wavelength 500 nm. falls on it with an intensity of ( 0.5 mathrm{W} / mathrm{cm}^{2}, ) striking the curved surface in a direction which is perpendicular to the flat face of the hemisphere is: (Assume the collisions to be perfectly inelastic) A. ( 5.2 times 10^{-13} N ) В. ( 5.2 times 10^{-12} N ) ( mathrm{c} cdot 5.22 times 10^{-9} mathrm{N} ) D. 0 n |
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154 | A ( alpha ) – particle is accelerated through a potential difference of ( V ) volts from rest. The de-Broglie wavelength associated with it is (in angstrom): A ( cdot sqrt{frac{150}{V}} ) в. ( frac{0.286}{sqrt{V}} ) c. ( frac{0.101}{sqrt{V}} ) D. ( frac{0.983}{sqrt{V}} ) |
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155 | If the mass of a microscopic particle a well as its speed are halved, the debroglie wavelength associated with the particle will A. increased by a factor more than 2 B. increases by a factor of 2 c. decreases by a factor of 2 D. decrease by a factor more than 2 |
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156 | A body of mass ( m ) is dropped freely from a height ( h ). The de-Broglie wavelength of the body as it reaches the ground is: A ( cdot frac{h}{sqrt{g H}} ) в. ( frac{h}{m sqrt{g H}} ) c. ( frac{h}{2 sqrt{g H}} ) D. ( frac{h}{m sqrt{2 g H}} ) |
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157 | For intensity ( I ) of a light of wavelength ( mathbf{5 0 0 0} boldsymbol{A} ) the photoelectron saturation current is ( 0.40 mu A ) and stopping potential is ( 1.36 V, ) the work function of metal is: A . 2.47 ev B. 1.36 ev c. 1.10 ev D. 0.43 ev |
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158 | The kinetic energy of most energetic electrons emitted from a metallic surface is doubled when the wavelength of the incident radiation is changed from 400 nm to 310 nm. The work function of the metal is : A ( .0 .9 e V ) B. 1.7 eV c. 2.2 eV D. 3.1 eV |
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159 | 45. The kinetic energy of most energetic electrons emitted from a metallic surface is doubled when the wavelength a of the incident radiation is changed from 400 nm to 310 nm. The work function of the metal is (a) 0.9 eV (b) 1.7 eV (c) 2.2 eV (d) 3.1 eV |
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160 | 60. A photon of wavelength 0.1 Å is emitted by a helium atom as a consequence of the emission of photon. The KE gained by helium atom is (a) 0.05 eV (b) 1.05 eV (c) 2.05 eV (d) 3.05 eV |
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161 | SICULUJ 50. In the experiment on photoelectric effect, the graph between Ex(max) and v is found to be a straight line as shown in figure. The threshold freq- uency and Planck’s 0 + constant according to 27 2 3 4 6 8 10 this graph are ux (10)1851 (a) 3.33 x 1018 -, 6x 10-34 J-s (b) 6 x 10185-4, 6x 10-34 J-s (c) 2.66 x 1018s!, 4 x 10-34 J-s (d) 4 x 10185-1,3 x 10-34 J-s EK (Max)* 10-15 joule |
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162 | The de-Broglie wavelength of an electron in the ground state of the hydrogen atom is : A ( cdot pi r^{2} ) в. ( 2 pi r ) ( c . pi r ) D. ( sqrt{pi r} ) |
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163 | Threshold wavelength depends on A. Frequency of incident radiation B. Work function of the substance C. Velocity of electrons D. Energy of electrons |
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164 | The wavelength of de broglie waves associated with a beam of protons of kinetic energy ( 5 times 10^{2} mathrm{eV} ) (Mass of each photon ( =mathbf{1 . 6 7} times mathbf{1 0}^{-mathbf{2 7}} mathbf{K g} ) ( boldsymbol{h}=mathbf{6 . 6 2} times mathbf{1 0}^{-mathbf{3 4}} mathbf{J s} ) A. ( 2.42 times 10^{-12} mathrm{m} ) B . ( 4.24 times 10^{-12} mathrm{m} ) c. ( 1.82 times 10^{-12} mathrm{m} ) D. ( 1.28 times 10^{-12} mathrm{m} ) |
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165 | The de-Broglie wavelength of an electron travelling with ( 10 % ) of velocity of light is equal to: A. ( 242.4 mathrm{pm} ) B. 24.2pm c. ( 2.42 mathrm{pm} ) D. 0.2424 pm |
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166 | In Millinkan’s oil drop experiment, a charged oil drop of mass ( 3.2 times 10^{-14} k g ) is held stationary between parallel plates ( 6 m m ) apart, by applying a potential difference of ( 1200 V ) between them. How many electrons does the oil drop carry? ( left(text { Given } g=10 m s^{-2}right) ) A. 7 B. 8 ( c cdot 9 ) D. 10 |
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167 | What is the ratio of wavelength of radiations emitted, when an electron in hydrogen atom jumps from fourth orbit to second orbit and from third orbit to second orbit? A . 27 : 25 B. 20:27 c. 20: 25 D. 25 : 27 |
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168 | A quartz lamp with iodine vapour releases ultraviolet light which falls on a photoelectric cell. If a thick glass plate is now introduced between the lamp and photoelectric cell then: A. the photoelectric current increases B. the maximum kinetic energy of photoelectrons decreases c. the photoelectric current decreases D. the maximum kinetic energy of photoelectrons increases |
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169 | For the Bohr’s first orbit of circumference ( 2 pi r, ) the de-Broglie wavelength of revolcing electron will be. A ( .2 pi r ) B . ( pi r ) c. ( frac{1}{2 pi r} ) D. ( frac{1}{4 pi r} ) |
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170 | 33. In Q. 32, if the intensity of light is made 410, then the stopping potential will become (a) 1.36 x 1 V (b) 1.36×2 V (c) 1.36X3 V (d) 1.36 X 4 V @ 1.36X1V (136×2 V |
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171 | ILLUSTRATION 28.4 A plate of mass 10 g is in equilibrium in air due to the force exerted by a light beam on the plate. Calculate power of the beam. Assume that the plate is perfectly absorbing. |
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172 | Which metal will be suitable for a photoelectric cell using light of wavelength ( 4000 A ) The work functions of sodium and copper are respectively 2eV and ( 4 e v ) A. Sodium B. Copper c. Both D. None of these |
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173 | If the cathode is cesium ( (phi=1.9 e V) ) what will be the cut off voltage? A. zero B . 0.36 V c. ( 0.46 mathrm{v} ) D. ( 0.56 mathrm{v} ) |
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174 | 20. This question has Statement 1 and Statement 2. Of the four choices given after the statements, choose the one that best describes the two statements Statement 1: A metallic surface is irradiated by a monochromatic light of frequency f> fo (the threshold frequency). The maximum kinetic energy and the stopping potential are Kmax and V, respectively. If the frequency incident on the surface is doubled, both the Kmax and Voare also doubled. Statement 2: The maximum kinetic energy and the stopping potential of photoelectrons emitted from a surface are linearly dependent on the frequency of incident light. (a) Statement 1 is true but statement 2 is false. (b) Statement 1 is true, statement 2 is true, statement 2 is the correct explanation of statement 1. (c) Statement 1 is true, statement 2 is true, statement 2 is not the correct explanation of statement 1. (d) Statement 1 is false but statement 2 is true. (AIEEE 2011) |
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175 | (d) 41 58. A homogeneous ball (mass = m) of ideal black material at rest is illuminated with a radiation having a set of photons (wavelength = 2), each with the same momentum and the same energy. The rate at which photons fall on the ball is n. The linear acceleration of the ball is (a) mNnh (b) nh/m2 (c) nh/(27)(m2) (d) 2pmNinh sd be 104 21 |
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176 | Show that it is not possible for a photon to be completely absorbed by a free electron. |
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177 | Two identical photocathodes receive light of frequencies ( f_{1} ) and ( f_{2} ). If the velocities of the photoelectrons (of mass ( m ) ) coming out are ( v_{1} ) and ( v_{2} ) respectively, then A. [ v_{1}-v_{2}=left[frac{2 h}{m}left(f_{1}-f_{2}right)right]^{frac{1}{2}} ] B. ( v_{1}^{2}-v_{2}^{2}=frac{2 h}{m}left(f_{1}-f_{2}right) ) c. ( quad v_{1}+v_{2}=left[frac{2 h}{m}left(f_{1}-f_{2}right)right]^{frac{1}{2}} ) D. ( v_{1}^{2}+v_{2}^{2}=frac{2 h}{m}left(f_{1}-f_{2}right) ) |
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178 | A metal surface is illuminated by light of two different wavelengths ( 248 n m ) and ( 310 n m . ) The maximum speeds of the photoelectrons corresponding to these wavelengths are ( u_{1} ) and ( u_{2} ) respectively. If the ratio ( u_{1}: u_{2}=2: 1 ) and ( h c=1240 e V n m, ) the work function of the metal is nearly: ( mathbf{A} cdot 3.7 mathrm{eV} ) B. ( 3.2 e V ) c. ( 2.8 e V ) D. ( 2.5 e V ) |
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179 | ILLUSTRATION 28.2 A bulb lamp emits light of mean wavelength of 4500 Å. The lamp is rated at 150 W and 8% of the energy appears as emitted light. How many photons are emitted by the lamp per second? |
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180 | If there are two de-Broglie waves formed in an orbit of H-atom then the energy of electron in that orbit is. A. ( -3.4 e V ) B. ( -13.6 e V ) c. ( -9.06 e V ) D. ( 1.51 mathrm{eV} ) |
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181 | What is the De-Broglie wavelength associated with the hydrogen electron in its third orbit : A ( .9 .96 times 10^{-10} mathrm{cm} ) В. ( 9.96 times 10^{-8} mathrm{cm} ) ( mathrm{c} cdot 9.96 times 10^{4} mathrm{cm} ) D. ( 9.96 times 10^{8} mathrm{cm} ) |
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182 | If the kinetic energy of the moving particle is ( boldsymbol{E} ), then the de Broglie wavelength is A ( cdot lambda=frac{h}{sqrt{2 m E}} ) B. ( lambda=frac{sqrt{2 m E}}{h} ) c. ( lambda=h sqrt{2 m E} ) D. ( lambda=frac{h}{E sqrt{2 m}} ) |
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183 | 67. A sodium metal piece is illuminated with light of wavelength 0.3 um. The work function of sodium is 2.46 eV. For this situation, mark out the correct statement(s). (a) The maximum kinetic energy of the ejected photoelectrons is 1.68 eV (b) The cut-off wavelength for sodium is 505 nm (c) The minimum photon energy of incident light for photoelectric effect to take place is 2.46 eV (d) All of the above |
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184 | The de-Broglie wavelength of a neutron ( operatorname{at} 927^{0} mathrm{C} ) is ( lambda . ) Its wavelength at ( 27^{0} mathrm{C} ) is: ( A cdot frac{lambda}{2} ) B. ( lambda ) ( c cdot 2 lambda ) D. ( 4 lambda ) |
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185 | Why we do not observe de Broglie wave in daily life? | 12 |

186 | 11. The eye can detect 5 x 104 photons per square metre per sec of green light (a = 5000 Å) while the ear can detect 10-$(W/m?). The factor by which the eye is more sensitive as a power detector than the ear is close to be (a) 5 (b) 10 (d) 15 olib b on (c) 106 |
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187 | If an electron and a proton have the same de-Broglie wavelength, then the kinetic energy of the electron is : A. zero B. Less than that of a proton c. More than that of a proton D. Equal to that of a proton |
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188 | On increasing the applied potential difference in X-ray tube This question has multiple correct options A. The intensity of emitted radiation increases. B. The minimum wavelength of emitted radiation increases c. The intensity of emitted radiation remains unchanged. D. The minimum wavelength of emitted radiation decreases |
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189 | The work function of aluminium is 4.2 eV. If two photons, each of energy 3.5 eV strike an electrons of aluminium, then emission of electrons A. Will be possible B. Will not be possible c. Data is incomplete D. Depends upon the density of the surface |
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190 | Photon having the energy equivalent to the binding energy of 4th state of ( boldsymbol{H} boldsymbol{e}^{+} ) atom is used to eject an electron from the metal surface of work function 1.4 eV. If electrons are further accelerated through the potential difference of ( 4 mathrm{V} ) then determine the minimum value of de-Broglie wavelength associated with the electron. в. 2.5 А ( ^{text {о }} ) ( c cdot 7.6 A^{circ} ) D. ( 10 A^{circ} ) |
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191 | The frequency and the intensity of a beam of light falling on the surface of a photoelectric material are increased by a factor of two. This will: A. Increase the maximum kinetic energy of the photoelectrons by 2 and photoelectric current by a factor of ( 1 / 2 ) B. Increase the maximum kinetic energy of the photoelectrons, and increase the photoelectric current by a factor of 2 C. Increase the maximum kinetic energy of the photoelectrons by a factor of 2 and will have no effect on the magnitude of the photoelectric current produced D. Not produced any effect on the kinetic energy of the emitted electrons but will increase the photoelectric current by a factor of 2 |
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192 | Calculate the de Broglie wavelength of an electron having kinetic energy of ( 1.6 times 10^{-6} ) erg ( left(m_{e}=9.11 timesright. ) ( mathbf{1 0}^{-mathbf{2 8}} boldsymbol{g}, boldsymbol{h}=mathbf{6 . 6 2} times mathbf{1 0}^{-mathbf{2 7}} mathbf{e r g}-boldsymbol{s e c} ) B . ( 0.00029 A^{circ} ) c. ( 0.0122 A^{circ} ) D. ( 1.29 A^{circ} ) |
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193 | In H-atom, if ‘x’ is the radius of the first Bohr orbit, de Broglie wavelength of an electron in 3rd orbit is : ( mathbf{A} cdot 3 pi x ) в. ( 6 pi x ) c. ( frac{9 x}{2} ) D. ( frac{x}{2} ) |
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194 | A ruby laser produces radiations of wavelengths, ( 662.6 mathrm{nm} ) in pulse duration are ( 10^{-6} ) s. If the laser produces ( 0.39 mathrm{J} ) of energy per pulse, how many photons are produced in each pulse? A ( cdot 1.3 times 10^{9} ) B . ( 1.3 times 10^{18} ) c. ( 1.3 times 10^{27} ) D. ( 3.9 times 10^{18} ) |
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195 | An ( alpha- ) particle and a proton have their masses in the ratio 4: 1 and charges in the ratio 2: 1 Find ratio of de-Broglie wavelengths |
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196 | Gases begin to conduct electricity at low pressure because: A. at low pressure gases turn to plasma B. colliding electrons can acquire higher kinetic energy due to increased mean free path leading to ionisation of atoms C . atoms break up into electrons and protons D. the electrons in atoms can move freely at low pressure |
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197 | Draw a neat, labelled energy level diagram for H atom showing the transitions. Explain the series of spectral lines for H atom, whose fixed inner orbit numbers are 3 and 4 respectively. The work functions for potassium and caesium are ( 2.25 mathrm{eV} ) and 2.14eV respectively. Is the photoelectric effect possible for either of them if the incident wavelength is ( 5180 A ? ) [Given: Planck’s constant= 6.63 ( x ) ( 10^{-34} mathrm{J}_{. mathrm{S}} ) Velocity of light ( =3 times 10^{8} m / s ; 1 e V= ) ( left.mathbf{1} . mathbf{6} times mathbf{1 0}^{-mathbf{1 9}} mathbf{J}right] ) |
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198 | Find the frequency of 1 MeV photon. Given wavelength of a ( 1 mathrm{keV} ) photon is ( 1.24 times 10^{-9} m ) Hint: ( boldsymbol{E}=boldsymbol{h} boldsymbol{nu} ) |
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199 | A material particle with a rest mass ( m_{0}^{prime} ) is moving with speed of light ‘c’ The de-Broglie wavelength associated is given by ( ^{A} cdot frac{h}{m_{0} c} ) в. ( frac{m_{0}}{h} ) c. zero ( D cdot infty ) |
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200 | 41. Light of wavelength a strikes a photoelectric surface and electrons are ejected with kinetic energy K. If Kis to be increased to exactly twice its original value, the wavelength must be changed to l’ such that (a) X’ 1/2 (c) 2> X’> N2 (d) X = N2 |
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201 | For wave connected with proton, debroglie wavelength change by ( 0.25 % ) if its momentum change by ( P_{0} ) initial momentum = A. ( 100 P_{0} ) в. ( frac{P_{0}}{400} ) c. ( 401 P_{0} ) D. ( frac{P_{0}}{100} ) |
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202 | A proton and an electron are accelerated by same potential difference starting from rest have de- Brogile wavelength ( lambda_{p} ) and ( lambda_{e^{*}} ) A ( cdot lambda_{e}=lambda_{p} ) B . ( lambda_{0}lambda_{p} ) D. none of these |
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203 | 37. The work function of a metallic surface is 5.01 eV. The photoelectrons are emitted when light of wavelength 2000 A falls on it. The potential difference applied to stop the fastest photoelectrons is ſh = 4.14 x 10- eVs] (a) 1.2 V (b) 2.24 V (c) 3.6 V (d) 4.8 V |
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204 | Energy equivalent to ( 10.00 mathrm{cm}^{-1} ) is: A ( .2 .0 times 10^{-22} ) J per atom B . 28.6 ( times 10^{-3} ) kcal.mol ( ^{-1} ) photon c. ( 12.0 times 10^{-2} k J . m o l^{-1} ) photon D. All of the above |
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205 | In the Millikan’s oil drop experiment the oil drop is subjected to a horizontal electric field of ( 4 mathrm{N} / mathrm{C} ) and the drop moves with a constant velocity making an angle ( 45^{0} ) to the horizontal. If the weight of the drop is W. The charge on the drop is (neglect buoyancy) A. w B. W/4 c. w/2 D. 3W/4 |
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206 | Select the incorrect statements about the wave function? A. ( psi ) may be zero B. ( psi ) must be single value, continuous C . ( psi ) has no physical significance D. ( psi ) gives the probability density of finding electrons. |
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207 | Two particles ( A ) and ( B ) have de-Broglie’s wavelengths ( 30 A ) and ( 20 A, ) combined to form a particle C. Momentum is conserved in this process. The possible de-Broglie’s wavelength of C is : (the motion is one dimensional) A ( cdot 12 AA ) в. 20 , ( c .10 hat{A} ) D. 22 a |
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208 | Find the energy of photon in each of the following: A. Microwaves of wavelength ( 1.5 mathrm{cm} ) B. Red light of wavelength 660 nm C. Radiowaves of frequency ( 96 M H z ) D. ( X- ) rays of wavelength 0.17 nm |
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209 | Choose the correct statement A. Any charged particle in rest is accompanied by matter waves. B. Any uncharged particle in rest is accompanied by matter waves. C. The matter waves are waves of zero amplitude. D. The matter waves are waves of probability amplitude. |
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210 | Calculate the maximum kinetic energy (in eV) of the emitted photoelectrons. A . 1.5 B. 2.36 c. 3.85 D. 4.27 |
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211 | Assertion An electron cannot exist in the nucleus. Reason The de Broglie wavelength of an electron is much smaller than the diameter of Read the above assertion and reason |
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212 | Show that de Broglie wavelength of electrons accelerated ( V ) volts is very nearly given by: ( lambda(i n dot{A})=frac{150^{1 / 2}}{V} ) |
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213 | represents the variation of particle momentum with associated de Broglie wavelength? ( mathbf{A} ) B. ( c ) ( D ) |
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214 | The voltage required to balance an oil drop carrying 10 electrons between the plates of a capacitor which are ( 10 mathrm{mm} ) apart, is (Given mass of the oil drop= ( left.mathbf{3} cdot mathbf{2} times mathbf{1 0}^{-mathbf{1 5}} mathbf{k g}, boldsymbol{e}=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{1 9}} mathbf{C}right) ) A . ( 16 v ) B. 160 V c. ( 196 v ) D. ( 19.6 v ) |
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215 | Radiation of two photon energies twice and five times the work function of metal are incident successively on the metal surface. The ratio of the maximum velocity of photoelectrons emitted is the two cases will be : A .1: 2 B . 2: 1 c. 1: 4 D. 4: 1 |
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216 | Write the formula for de Broglie wavelength. An electron is moving with speed of ( 0.5 times 10^{3} m / s . ) Find the de Broglie wavelength associated with it. |
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217 | Light of frequency ( v ) is incident on a metal of threshold frequency ( v_{0} . ) Then work function of metal will be: A ( . h v ) в. ( h v_{0} ) ( mathbf{c} cdot hleft(v-v_{0}right) ) D. ( hleft(v+v_{0}right) ) |
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218 | The de Broglie wavelength of an electron accelerated by an electric field of ( V ) volt is given by: A ( cdot lambda=frac{1.23}{sqrt{m}} ) в. ( lambda=frac{1.23 m}{sqrt{h}} m ) c. ( lambda=frac{1.23}{sqrt{V}} n m ) D. ( lambda=frac{1.23}{V} ) |
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219 | If the momentum of an electron is changed by ( P, ) then the de-Broglie wavelength associated with it changes by ( 0.5 % ). The initial momentum of electron will be : ( mathbf{A} cdot 400 P ) в. ( frac{P}{200} ) ( c cdot 100 P ) D. 200P |
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220 | de-Broglie wavelength associated with an electron revolving in the ( n^{t h} ) state of hydrogen atom is directly proportional to A ( . n ) в. ( frac{1}{n} ) c. ( n^{2} ) D. ( frac{1}{n^{2}} ) |
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221 | 3. Two identical photocathodes receive light of frequencies fi and f2. If the velocities of the photoelectrons (of mass m) coming out are, respectively, V, and V2, then (a) v, – vz = [phy Cr, -1))”? (b) vi – vi = m (81-f2) (c) vi + vz = [ Pahle (5 +5] (d) vi – v; = Pho (5, + f2) (AIEEE 2003) |
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222 | Two particles ( A_{1} ) and ( A_{2} ) of masses ( boldsymbol{m}_{1}, boldsymbol{m}_{2}left(boldsymbol{m}_{1}>boldsymbol{m}_{2}right) ) have the same de Broglie wavelength. Then A. their momenta are the same B. their energies are the same. c. momentum of ( A_{1} ) is less than momentum of ( A_{2} ) D. energy of ( A_{1} ) is more than the energy of ( A_{2} ) |
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223 | ILLUSTRATION 28.7 An electron microscope uses electrons accelerated by a voltage of 50 kV. Determine the de Broglie wavelength associated with the electrons. If other factors (such as numerical aperture, etc.) are taken to be roughly the same, how does the resolving power of an electron microscope compare with that of an optical microscope which uses yellow light? |
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224 | In a photo-electric cell, a retarding potential of ( 0.5 V ) is required to block the movement of electrons from the cathode when monochromatic light of wavelength ( 400 n m ) is incident on its surface. Find the work function of the material of the cathode. |
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225 | A proton and electron are accelerated by same potential difference starting from the rest have de-Broglie wavelength ( lambda_{p} ) and ( lambda_{e} ) A ( cdot lambda_{e}=lambda_{p} ) в. ( lambda_{e}lambda_{p} ) D. none of these |
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226 | The potential energy of a particle of mass ( m ) is given by ( V(x)= ) ( left{begin{array}{cc}boldsymbol{E}_{0} mathbf{0} & leq boldsymbol{x} leq mathbf{1} \ mathbf{0} & boldsymbol{x}>mathbf{1}end{array}right} ) ( lambda_{1} ) and ( lambda_{2} ) are the de-Broglie wavelengths of the particle, when ( 0 leq ) ( x leq 1 ) and ( x>1 ) respectively. If the total energy of particle is ( 2 E_{0} ) |
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227 | A radiation is incident on a metal of work function ( 2.3 e V . ) The incident radiation is ( 600 n ) m.lf the total energy of incident radiation is ( 23 J ), then the number of photoelectrons is A. zero B ( .<10^{4} ) ( mathbf{c} .=10^{4} ) D. ( infty ) |
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228 | The ratio of the wavelengths of a photon and that of an electron of same energy ( boldsymbol{E} ) will be ( [boldsymbol{m} text { is mass of electron }] ) A ( cdot sqrt{frac{2 m}{E}} ) в. ( sqrt{frac{E}{2 m}} ) ( c cdot c sqrt{frac{2 m}{E}} ) D. ( sqrt{frac{E c}{2 m}} ) |
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229 | len 6. Ka wavelength emitted by an atom of atomic number Z= 11 is 2. The atomic number for an atom that emits K, radiation with wavelength 42 is (a) Z=6 (b) Z=4 (c) Z= 11 (d) Z=44 and |
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230 | If the ratio of de-Broglle wavelength of a proton and an ( alpha- ) particle is 1: 3 then |
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231 | A monochromatic source of light operating at ( 200 mathrm{W} ) emits ( 4 times 10^{20} ) photons/second. Then the wavelength of light used is A. 3000 ( A^{0} ) B . ( 5000 A^{0} ) c. ( 4000 A^{0} ) D. ( 6000 A^{circ} ) |
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232 | Assertion If the potential difference applied to an electron is made 4 times, the de Broglie wavelength associated is halved. Reason On making potential difference 4 times, velocity is doubled and hence ( d ) is halved. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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233 | 8. The minimum intensity of light to be detected by human eye is 10-W/m?. The number of photons of wavelength 56% 10′ m entering the eye, with pupil area 10 m, per second for vision will be nearly (a) 100 (b) 200 (e) 300 (d) 400 |
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234 | One milliwatt of light of wavelength ( lambda=4560 A ) is incident on a cesium metal surface. Calculate the electron current liberated. Assume a quantum efficiency of ( boldsymbol{eta}=mathbf{0 . 5 %} ). [Work function for cesium ( =1.89 e V] ) take ( h c= ) ( 12400 e V-A ) |
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235 | A particle of mass ( mathrm{m} ) is projected from ground with velocity u making angle ( theta ) with the vertical. The de Broglie wavelength of the particle at the highest point is ( A cdot infty ) B. ( h / m u ) sin ( theta ) c. ( h / m u cos theta ) ( mathbf{D} cdot h / m u ) |
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236 | A particle moves in a closed orbit around the origin, due to a force which is directed towards the origin. The de Broglie wavelength of the particle varies cyclically between two values ( lambda_{1} ) and ( lambda_{2} ) with ( lambda_{1}>lambda_{2} . ) Which of the following statement is true? A. The particle could be moving in an circular orbit with origin as centre B. The particle could be moving in an parabolic orbit with origin as its focus C. When the de Broglie wave length is ( lambda_{1} ), the particle is nearer the origin than when its value is ( lambda_{2} ) D. When the de Broglie wavelength is ( lambda_{2} ), the particle is nearer the origin than when its value is ( lambda_{1} ) |
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237 | The de Broglie wavelength of a particle of mass 1 gram and velocity 100 ms ( ^{-1} ) is: A. ( 6.63 times 10^{-35} ) В. ( 6.63 times 10^{-34} ) c. ( 6.63 times 10^{-33} ) D. ( 6.63 times 10^{-32} ) |
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238 | An electron in an excited state of ( L i^{2+} ) ion has angular momentum 3 h/2 ( pi ). The de Broglie wavelength of the electron in this state in ( p pi alpha_{0} ) (where ( alpha_{0} ) is the Bohr radius). The value of ( p ) is : |
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239 | If ( lambda_{0} ) is the de Broglie wavelength for a proton accelerated through a potential difference of ( 100 mathrm{V}, ) the de Broglie wavelength for ( alpha ) -particle accelerated through the same potential difference is A ( cdot 2 sqrt{2} lambda_{0} ) B. ( frac{lambda_{0}}{2} ) ( c cdot frac{lambda_{0}}{2 sqrt{2}} ) D. ( frac{lambda_{0}}{sqrt{2}} ) |
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240 | The work function of tungsten coated with Barium Oxide is nearly A. 5 ev B. 10 ev ( c cdot 1 e v ) D. 0.01 ev |
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241 | If alpha particle, proton and electron move with the same momentum, then their respective de-Broglie wavelengths ( lambda_{alpha}, lambda_{p}, lambda_{e} ) are related as A ( cdot lambda_{alpha}=lambda_{p}=lambda_{e} ) B . ( lambda_{alpha}<lambda_{p}lambda_{p}>lambda_{e} ) D. ( lambda_{p}>lambda_{e}>lambda_{alpha} ) E ( cdot lambda_{p}<lambda_{e}<lambda_{alpha} ) |
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242 | Write object of Dacisson and Germer’s experiment. Draw a labelled diagram of its parctical arrangement. | 12 |

243 | Threshold wavelength for a metal having work function ( omega_{0} ) is ( lambda . ) Then the threshold wavelength for the metal having work function ( 2 omega_{0} ) is ( A cdot 4 lambda ) B. 2lambda ( c cdot lambda / 2 ) D. ( lambda / 4 ) |
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244 | The process of photoelectric emission depends on A. Temperature of incident light B. Nature of surface c. speed of emitted photo electrons D. Speed of the incident light |
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245 | In photoelectric effect, the slope of the straight line graph between stopping potential and frequency of the incident light gives the ratio of Planck’s constant to A. Charge of electron B. Work function c. Photoelectric current D. K.E. of electron |
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246 | The relation between energy E and momentum p of a photon is A ( . E=p c ) B. ( E=frac{p}{c} ) c. ( p=E c ) D. ( quad E=frac{p^{2}}{c} ) |
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247 | The work function for the surface of aluminium is ( 4.2 mathrm{eV} ). How much potential difference will be required to stop the emission of maximum energy electrons emitted by light of ( 2000 dot{A} ) wavelength? What will be the wavelength of that incident light for which stopping potential will be ( 0 ? ) |
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248 | Assertion When monochromatic light falls on a photosensitive material, the number of photo electrons emitted per second is ( n ) and their maximum kinetic energy is ( K_{m a x} . ) If the intensity ( I ) of the incident light is doubled, ( n ) is doubled but ( K_{m a x} ) remains the same. Reason The value of ( n ) is directly proportional to ( I ) but ( K_{max } ) is independent of ( I ) A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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249 | What are de-Broglie waves? Establish the de-Broglie wavelength equation. | 12 |

250 | The electricity produced by creating photo electrons is called: A. Photoelectricity B. Static electricity c. Thermal electricity D. Piezoelectricity |
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251 | Define the photoelectric effect. Write the laws of the photoelectric effect. | 12 |

252 | 1. Sodium and copper have work functions 2.3 eV and 4.5 eV, respectively. Then the ratio of the wavelengths is nearest to (a) 1:2 (b) 4:1 (c) 2:1 (d) 1:4 (AIEEE 2002) | |
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253 | Find the minimum wavelength of ( X ) -ray produced if ( 10 mathrm{kV} ) potential difference is applied across the anode and cathode of the tube. A ( cdot 12.4 mathrm{A}^{circ} ) B. 12.4 nm ( c cdot 1.24 mathrm{nm} ) D. ( 1.24 mathrm{A}^{circ} ) |
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254 | The work function of a metal is ( 6 e V ). If two photons each having energy ( 4 e V ) strike with the metal surface (i) Will the emission be possible? (ii) Why? |
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255 | 5. The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately (a) 540 nm (b) 400 nm (c) 310 nm (d) 220 nm (AIEEE 2004) 11: 13 nad 1 11 |
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256 | The work function of metal is in the range of ( 2 e V ) to ( 5 e V ). Find which of the following wavelength of light cannot be used for photoelectric effect: (Consider, Plank constant ( =mathbf{4} times ) ( 10^{-15} e V s, ) velocity of light ( =3 x ) ( left.mathbf{1 0}^{mathbf{7}} boldsymbol{m} / boldsymbol{s}right) ) A. 510 nm B. 650 nm ( c .400 mathrm{nm} ) D. 570 nm |
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257 | Define : photoelectric work function. |
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258 | An electron and a proton have the same De Broglie wavelength. Then the kinetic energy of the electron is: A. zero B. Infinity c. Equal kinetic energy of proton D. Greater than the kinetic energy of proton |
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259 | The time taken by a photoelectron to come Out after the photon strikes is approximately. ( mathbf{A} cdot 10^{-1} s ) B. ( 10^{-2} s ) ( mathbf{c} cdot 10^{-10} s ) D. ( 10^{-16} s ) |
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260 | 64. If the short wavelength limit of the continous spectrum coming out of a Coolidge tube is 10 Å, then the de Broglie wavelength of the electrons reaching the target metal in the Coolidge tube is approximately (a) 0.3 Å (b) 3 Å (c) 30 Å (d) 10 Å |
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261 | The energy of a photons is equal to the kinetic energy of a proton. If ( lambda_{1} ) is the de Broglie wavelength of a proton, ( lambda_{2} ) the wavelength associated with the photon, and if the energy of the photon is ( mathrm{E} ), then ( left(lambda_{1} / lambda_{2}right) ) is proportional to: ( mathbf{A} cdot E^{4} ) B. ( E^{1 / 2} ) c. ( E^{2} ) D. ( E ) |
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262 | Work function of three metals ( A, B, C ) are ( 4.5 mathrm{eV}, 4.3 mathrm{eV} ., 3.5 ) ev respectively. If a light of wavelength 4000 A is incident on the metals, then A. photoelectron are emitted from ( c ) B. photoelectrons are emitted from A c. photoelectrons are emitted from B D. photoelectron will not emitted from all the surfaces |
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263 | An electron and a photon have same wavelength of ( 10^{-9} mathrm{m} . ) If ( mathrm{E} ) is the energy of the photon and p is the momentum of the electron, the magnitude of E/p in ( mathrm{S} ) units is? A. ( 1.00 times 10^{-9} ) B. ( 1.50 times 10^{8} ) c. ( 3.00 times 10^{8} ) D . ( 1.20 times 10^{7} ) |
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264 | Calculate the de Broglie wavelength for a beam of electron whose energy is 100 ( mathrm{eV}: ) ( A cdot 1 A ) B. 1.23 A c. ( 2.46 mathrm{A} ) D. None of these |
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265 | A proton, a neutron, an electron and an ( alpha ) -particle have same energy. Then their de Broglie wavelengths compare as: ( mathbf{A} cdot lambda_{p}=lambda_{n}>lambda_{e}>lambda_{alpha} ) B . ( lambda_{alpha}<lambda_{p}=lambda_{n}<lambda_{e} ) ( mathbf{c} cdot lambda_{e}lambda_{alpha} ) ( mathbf{D} cdot lambda_{e}=lambda_{p}=lambda_{n}=lambda_{alpha} ) |
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266 | When the light of frequency ( 2 v_{0} ) (where ( v_{0} ) is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is ( v_{1} ). When the frequency of the incident radiation is increased to ( 5 v_{0}, ) the maximum velocity of electrons emitted from the same plate is ( v_{2} ). The ratio of ( v_{1} ) to ( v_{2} ) is? A . 4: 1 B. 1: 2 c. 2: 1 D. 1: 4 |
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267 | Uncertainty in position of a 0.25 g particle is ( 10^{-5} mathrm{m} . ) The uncertainty in its velocity will be:- ( left(h=6.6 times 10^{-34} J sright) ) A. ( 1.2 times 10^{34} ) B . ( 2.1 times 10^{-29} ) c. ( 1.6 times 10^{-20} ) D. ( 1.7 times 10^{-9} ) |
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268 | Which one of the following is not dependent on the intensity of incident photon in a photoelectric experiment? A. work function of the surface B. kinetic energy of photo-electron c. stopping potential D. amount of photo-electric current |
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269 | A particle A with a mass ( m_{A} ) is moving with a velocity v and hits a particle B of mass ( m_{B} ) at rest. If motion is one dimensional and take the collision is elastic, then the change in the de Broglie wavelength of the particle A is ( ^{text {A }} frac{h}{2 m_{A} v}left[frac{left(m_{A}+m_{B}right)}{left(m_{A}-m_{B}right)}-1right] ) в. ( frac{h}{m_{A} v}left[frac{left(m_{A}-m_{B}right)}{left(m_{A}+m_{B}right)}-1right] ) c. ( frac{h}{m_{A} v}left[frac{left(m_{A}+m_{B}right)}{left(m_{A}-m_{B}right)}-1right] ) D. [ frac{2 h}{m_{A} v}left[frac{left(m_{A}+m_{B}right)}{left(m_{A}-m_{B}right)}+1right] ] |
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270 | ( WC U11 IIDU 36. In Q. 32, if the wavelength is changed to 4000 A, then stopping potential will become (a) 1.3 V (b) 3.40 V (c) 1.60 V (d) 1.97 V |
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271 | A parallel beam of monochromatic light of wavelength ( 663 mathrm{nm} ) is incident on a totally reflecting plane mirror. The angle of incident is ( 60^{circ} ) and the number of photons striking the mirror per second is ( 1.0 times 10^{19} . ) If the force exerted by light beam on the mirror is ( Y times 10^{-8} N . ) Find ( Y ) |
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272 | An electron microscope uses electrons accelerated by a voltage of ( 50 mathrm{kV} ) Determine the de-Broglie wavelength associated with the electrons. Taking other factors, such as numerical aperture etc. to be same, how does the resolving power of an electron microscope compare with what of an optical microscope which uses yellow light? |
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273 | The value of ( left(n_{2}+n_{1}right) ) and ( left(n_{2}^{2}-n_{1}^{2}right) ) for ( H e^{+} ) ion in atomic spectrum are 4 and 8 respectively. The wavelength of emitted photon when electron jump from ( n_{2} ) to ( n_{1} ) is: ( ^{mathbf{A}} cdot frac{32}{9} R_{H} ) в. ( frac{9}{32} R_{H} ) c. ( frac{9}{32 R_{H}} ) D. ( frac{32}{9 R_{H}} ) |
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274 | A particle of mass ( mathrm{M} ) at rest decays into two masses ( m_{1} ) and ( m_{2} ) with non-zero velocities. The ratio ( lambda_{1} / lambda_{2} ) of de Broglie wavelengths of particles is A ( cdot m_{2} / m_{1} ) в. ( m_{1} / m_{2} ) c. ( sqrt{m_{1}} / sqrt{m_{2}} ) in D. 1: |
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275 | The work function of a surface of a photosensitive material is ( 6.2 e V . ) The wavelength of the incident radiation for which the stopping potential is ( 5 V ) lies in the: A. ultraviolet region B. ( X ) -ray region c. infrared region D. none of these |
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276 | If ( 10,000 V ) are applied across an ( X ) -ray tube, find the ratio of wavelength of the incident electrons and the shortest wavelength of ( X ) -ray coming out of the X-ray tube, given ( e / m ) of electron ( = ) ( 1.8 times 10^{11} C k g^{-1} ) ( mathbf{A} cdot 1: 10 ) B. 10: 1 c. 5: 1 D. 1: 5 |
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277 | An isotropic point source emits light with wavelength 500nm. The radiation power of the source is ( boldsymbol{P}=mathbf{1 0} boldsymbol{W} ). Find the number of photons passing through unit area per second at a distance of ( 3 m ) from the source A ( .5 .92 times 10^{17} / m^{2} s ) B . ( 2.23 times 10^{17} / m^{2} s ) c. ( 2.23 times 10^{18} / m^{2} s ) D. ( 5.92 times 10^{18} / m^{2} s ) |
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278 | A proton is fired from very far away towards a nucleus with charge ( Q=120 mathrm{e} ) where e is the electronic charge. It makes a closest approach of ( 10 mathrm{fm} ) to the nucleus. The de Broglie wavelength (in units of ( mathrm{fm} ) ) of the proton at its start is : (take the proton mass, ( boldsymbol{m}_{boldsymbol{p}}=(mathbf{5} / mathbf{3}) times ) ( 10^{-27} k g ) and ( boldsymbol{h} / boldsymbol{e}=mathbf{4 . 2} times mathbf{1 0}^{-15} boldsymbol{J} . boldsymbol{s} / boldsymbol{C} ; frac{1}{4 pi epsilon_{0}}=mathbf{9} times ) ( left.mathbf{1 0}^{9} boldsymbol{m} / boldsymbol{F} ; mathbf{1} boldsymbol{f} boldsymbol{m}=mathbf{1 0}^{-mathbf{1 5}} boldsymbol{m}right) ) ( A cdot 7 f m ) B. 8 fm ( c .9 f m ) D. ( 10 mathrm{fm} ) |
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279 | (a) More than 6.8 eV 56. A cesium photocell, with a steady potential difference of 60 V across it, is illuminated by a small bright light placed 1 m away. When the same light is placed 2 m away, the electrons crossing the photocell (a) each carry one-quarter of their previous momentum (b) each carry one-quarter of their pervious energy (c) are one-quarter as numerous (d) are half as numerous |
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280 | A proton when accelerated through a potential difference of ( V ) volt has a wavelength ( lambda ) associated with it. An ( alpha ) particle in order to have the same wavelength ( lambda ) must be accelerated through a p.d. of A. ( vee / 8 ) volt B. V/4 volt c. v volt D. 2v volt |
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281 | The equation for a wave travelling in ( x ) direction on a string is : ( y=3(sin 3.14 x- ) ( 314 t), ) then Find the maximum velocity of particle |
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282 | A monochromatic beam of electromagnetic radiation has an intensity of ( 1 W / m^{2} . ) Then the average number of photons per ( m^{3} ) for a ( 10 mathrm{MeV} ) ( gamma ) ray is ( ? ) A . 4166 B. 3000 c. 5000 D. 2083 |
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283 | Electrons used in an electron microscope are accelerated by a voltage of ( 25 mathrm{kV} ). If the voltage is increased to ( 100 mathrm{kV} ) then the de-Broglie wavelength associated with the electrons would? A. Increase by 2 times B. Decrease by 2 times c. Decrease by 4 times D. Increase by 4 times |
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284 | If the ionization energy for the hydrogen atom is ( 13 e V ), the energy required to excite it from the ground state to the next higher state is nearly A . ( 3.4 e V ) B. ( 10.2 e V ) c. ( 12.1 e V ) D. ( 1.5 e V ) |
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285 | Find the kinetic energy of this electron as it comes out of the metal A. 0.46 ev B. 0.31 ev ( c cdot 0.23 mathrm{ev} ) D. None of these |
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286 | On a photosensitive material, when frequency of incident radiation is increased by ( 30 % ) kinetic energy of emitted photo electrons increases from ( 0.4 e V ) to ( 0.9 e V . ) The work function of the surface is : A. ( 1 e V ) B. 1.267 eV c. ( 1.4 e V ) D. 1.8 eV |
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287 | Assertion Threshold wavelength of certain metal is ( lambda_{0} . ) Light of wavelength slightly less than ( lambda_{0} ) is incident on the plate. It is found that after some time the emission of electrons stops Reason The ejected electrons experience force of attraction due to development of positive. A. Assertion is incorrect but Reason is correct B. Both Assertion and Reason are correct and Reason is not the correct explanation for Assertion. C. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect and Reason is correct explanation for Assertion. |
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288 | 75. An electron beam accelerated from rest through a potential difference of 5000 V in vacuum is allowed to impinge on a surface normally. The incident current is mA and if the electrons come to rest on striking the surface the force on it is (a) 1.1924 x 10-ⓇN (b) 2.1 x 10-8N (c) 1.6 × 10-N (d) 1.6 × 10-N O |
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289 | Which wavelength of light has the LOWEST frequency? ( mathbf{A} cdot 2 m m ) B. ( 1 n m ) c. ( 10 n m ) D. ( 20 n m ) |
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290 | A voltage of ( 1.1 mathrm{V} ) is needed to stop the photocurrent generated when a monochromatic light of wavelength ( lambda=4000 A ) is incident on it. Find the work function of metal ( A cdot 2.3 mathrm{ev} ) B. 2 ev c. 4.2 ev D. None pf these |
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291 | An element undergoes reaction as shown: ( X+2 e-, ) energy released ( = ) ( 30.87 e V / ) atom. If the energy released, is used to dissociate 4 g of ( boldsymbol{H}_{2} ) molecules, equally into ( boldsymbol{H}^{+} ) and ( boldsymbol{H}^{*} ) where ( boldsymbol{H}^{*} ) is excited state of ( mathrm{H} ) atoms, where the electrons travels in in orbit whose circumference equal to four times it’s de Broglie’s wavelength. Determine the least moles of ( X ) that would be required: Given: I.E. of ( mathrm{H}=13.6 mathrm{eV} / ) atom, bond |
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292 | ILLUSTRATION 28.1 Calculate the number of photons emitted in 10 h by a 60 W sodium lamp (a = 5893 Å). ho |
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293 | The energy of a photon is ( 3 times 10^{-12} ) ergs. Its wavelength (in nm) will be: A .662 в. 1324 c. 66.2 D. 6.62 |
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294 | ILLUSTRATION 28.8 What is the energy in eV) of a photon of wavelength 12400 Å? |
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295 | What is the de-broglie wavelength for the electron of third class of hydrogen? ( mathbf{A} cdot 9.96 times 10^{-10} mathrm{cm} ) В. ( 9.96 times 10^{-8} mathrm{cm} ) ( mathbf{c} .9 .96 times 10^{4} mathrm{cm} ) D. ( 9.96 times 10^{8} mathrm{cm} ) |
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296 | Assertion In both radio activity and photoelectric effect electrons may be ejected. Reason In photoelectric effect and radio activity emission occurs only of unstable elements. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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297 | An electron (mass ( boldsymbol{m} ) ) with initial velocity ( vec{v}=v_{0} hat{i}+v_{0} hat{j} ) is an electric field ( vec{E}=-E_{0} hat{k} . ) If ( lambda_{0} ) is initial de- Broglie wave length at time ( t ) is given by ( A ) [ frac{lambda_{0}}{sqrt{1+frac{e^{2} E^{2} t^{2}}{2 m^{2} v_{0}^{2}}}} ] в. [ frac{lambda_{0} sqrt{2}}{sqrt{1+frac{e^{2} E^{2} t^{2}}{m^{2} v_{0}^{2}}}} ] c. [ frac{lambda_{0}}{sqrt{2+frac{e^{2} E^{2} t^{2}}{m^{2} v_{0}^{2}}}} ] D. [ frac{lambda_{0}}{sqrt{1+frac{e^{2} E_{0}^{2} t^{2}}{m^{2} v_{0}^{2}}}} ] |
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298 | Electron and proton are accelerated through one volt of potential difference, the ratio of their wavelengths is equal to: A. ( frac{m_{p}}{m_{e}} ) В ( cdot frac{m_{p} V_{e}}{m_{e} V_{p}} ) c. ( frac{m_{p}^{2}}{m_{e}^{2}} ) D. ( sqrt{frac{m_{p}}{m_{e}}} ) |
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299 | De-Broglie wavelength of an atom at absolute temperature ( boldsymbol{T} boldsymbol{K} ) will be A ( cdot frac{h}{sqrt{3 m K T}} ) в. ( frac{h}{m K T} ) c. ( frac{sqrt{2 m K T}}{h} ) D. ( sqrt{2 m K T} ) |
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300 | Graph is plotted between maximum kinetic energy of electron with frequency of incident photon in Photo electric effect. The slope of curve will be A. Charge of electron B. Work function of metal c. Planck’s constant D. Ratio of planck constant and charge of electron |
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301 | A light of wavelength ( lambda ) is incident on a metal sheet of work function ( phi=2 e V ) The wavelength ( lambda ) varies with time as ( lambda=3000+40 t, ) where ( lambda ) is in and ( t ) is in second. The power incident on metal sheet is constant at 100 W. This signal is switched on and off for time intervals of 2 minutes and 1 minute respectively. Each time the signal is switched on, the ( lambda ) start from an initial value of ( 3000 . ) The metal plate is grounded and electron clouding is negligible. The efficiency of photoemission is ( 1 %(h c=12400 e V) ) The time after which photo-emission will stop is A. 79 s B. 80 s c. ( 81 mathrm{s} ) D. 78 s |
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302 | Find the value of wave number ( (bar{V}) ) in term of Rydberg’s constant ( left(R_{H}right), ) when transition of electron takes place between two levels of ( H e^{+} ) ion, whose sum is 4 and difference is 2 A ( cdot frac{8}{9} R_{H} ) В . ( frac{32}{9} R_{H} ) c. ( frac{1}{9} R_{H} ) D. none of these |
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303 | 57. An image of the sun is formed by a lens of the focal length of 30 cm, on the metal surface of a photoelectric cell and a photoelectric current/is produced. The lens forming the image is then replaced by another of the same diameter but of focal length 15 cm. The photoelectric current in this case is (c) 27 (d) 41 |
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304 | A surface has work function ( 3.3 e V ) Which of the following will cause emission? A. ( 100 W ) incandascent lamp B. 40 ( W ) flouroscent lamp c. ( 20 W ) sodium lamp D. 20 ( W ) Hg lamp |
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305 | If the kinetic energy of the particle is increased to 16 times previous the percentage change in the deBrogille wavelength of the particle is | 12 |

306 | If the uncertainty in the position of proton is ( 6 times 10^{-8} m, ) then the minimum uncertainty in its speed will be: A ( cdot 1 mathrm{cms}^{-1} ) В. ( 0.52 mathrm{ms}^{-1} ) ( mathbf{c} cdot 1 mathrm{mms}^{-1} ) D. ( 100 mathrm{ms}^{-1} ) |
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307 | 10. Two metallic plates A and B, each of area 5 x 104 m2 placed parallel to each other at a separation of 1 cm Plo B carries a positive charge of 33.7 pc. A monochromatic beam of light, with photons of energy 5 eV each, start falling on plate A at t=0, so that 10’° photons fall on it per square meter per second. Assume that one photoelectron is emitted for every 10° incident photons. Also assume that all the emitted photoelectrons are collected by plate B and the work function of plate A remains constant at the value 2 eV. Electric field between the plates at the end of 10 seconds is (a) 2 x 10′ N/C (b) 103 N/C (c) 5 x 10′ N/C (d) Zero |
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308 | In photoelectric effect, the photoelectric current is independent of A. intensity of incident light B. potential difference applied between the two electrodes c. the nature of emitter material D. frequency of incident light |
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309 | Assertion The de-Broglie wavelength equation has significant for any microscopic and submicroscopic particles. Reason de-Broglie wavelength is inversely proportional tot he mass of the object, if its velocity is constant. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. Both Assertion and Reason are incorrect |
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310 | The work function of a substance is 4.0eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately A . ( 5400 A^{circ} ) в. ( 4000 A^{circ} ) c. ( 3100 A^{circ} ) D. 2200A ( ^{text {0 }} ) |
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311 | The work function for tungsten and sodium are ( 4.5 e V ) and ( 2.3 e V ) respectively. If threshold wavelength ( lambda ) for sodium is ( 5460 A ), the value of ( lambda ) for tungsten is ( mathbf{A} .5893 hat{A} ) в. 10683 , c. 2791 , D. 528 月 |
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312 | Light of wavelength ( lambda ) falls on a metal having work function ( h c / lambda_{0} ) Photoelectric effect will take place only if |
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313 | Calculate the de Broglie wavelength associated with a helium atom in a helium gas sample at ( 27^{circ} mathrm{C} ) and 1 at ( mathrm{m} ) pressure. ( mathbf{A} cdot 7.3 times 10^{-11} ) metre. B . ( 3.6 times 10^{-10} ) metre. c. ( 7.3 times 10^{-10} ) metre. D. ( 3.6 times 10^{-11} ) metre. |
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314 | 54. Ultraviolet light of wavelength 300 nm and intensity 1.0 Wm falls on the surface of a photosensitive material. If one per cent of the incident photons produce photo- electrons, then the number of photoelectrons emitted per second from an area of 1.0 cm of the surface is nearly (a) 9.61 x 1014 s-1 (b) 4.12 x 10135-1 (c) 1.51 x 1012 5-1 (d) 2.13 x 1011 3-1 |
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315 | An electron of mass ‘m’ and charge ‘w’ initially at rest gets accelerated by a constant electric field ‘E’. The rate of change of de-Broglie wavelength of this electron at time ‘t’ ignoring relativistic effects is ( ^{A} cdot-frac{h}{e E t^{2}} ) B. ( -frac{e h t}{E} ) c. ( -frac{m h}{e E t^{2}} ) D. ( frac{h}{e E} ) |
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316 | A particle having a mass of 1.0 mg has a velocity of ( 3600 k m / h ). Calculate the wavelength of the particle: ( left(h=6.626 times 10^{-27} e r g-s e cright) ) A ( cdot 6.626 times 10^{-28} mathrm{cm} ) B. ( 6.626 times 10^{-29} mathrm{cm} ) C. ( 6.626 times 10^{-30} mathrm{cm} ) D. ( 6.626 times 10^{-31} mathrm{cm} ) |
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317 | In a H-atom, an electron is in ( 2^{n d} ) excited state and its radius ( =4.75 AA ) Calculate de-broglie wavelength of the electron. A ( cdot frac{8.5 pi}{4} ) B. 0 с. ( frac{19 pi}{3} ), D. ( frac{9.5 pi}{3} ) |
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318 | A photon and electron have got the same de Broglie wavelength. Explain which has greater total energy. |
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319 | Name the unit in which work function of a metal is generally expressed. A. Newton B. Kilojoule ( c cdot e v ) ( D ) |
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320 | 71. The potential energy of a particle of mass m is given bu U(x) = {Bo; 05×51 x > 1 2, and I are the de-Broglie wavelengths of the particle when 0 <x 1 respectively. If the total energy of particle is 2Eo, the ratio will be (b) 1 (b) 1 blos (a) 2 (c) 2. |
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321 | Photon of frequency ( boldsymbol{v} ) has a momentum associated with it. If ( c ) is the velocity of light, the momentum is : ( mathbf{A} cdot v / c ) B. hv ( c ) c. ( h v / c^{2} ) D. ( h v / c ) |
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322 | An electron, ( alpha ) – particle and a proton have the same kinetic energy. A comparison of their de Broglie wavelengths yields: A ( cdot lambda_{p}>lambda_{a}lambda_{a}<lambda_{p} ) c. ( lambda_{a}<lambda_{p}<lambda_{e} ) D. ( lambda_{p}<lambda_{e}<lambda_{a} ) |
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323 | If the kinetic energy of a particle is increased by 16 times, the percentage change in the de Broglie wavelength of the particle is: A . 25% B. 75% c. 60% D. 50% |
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324 | A photon of light from which of the following electromagnetic radiations carries the greater amount of energy? A. Blue B. Green c. orange D. Red E. Yellow |
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325 | When a metal surface is illuminated by light of wavelengths ( 400 mathrm{nm} ) and 250 ( mathrm{nm}, ) the maximum velocities of the photoelectrons ejected are v and 2v respectively. The work function of the metal is A ( cdot 3.972 times 10^{-19} mathrm{J} ) В. ( 1.59 times 10^{-19} mathrm{J} ) D. ( 0.5 times 10^{-19} mathrm{J} ) |
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326 | Einstein was awarded a Noble Prize for: A. Photo electric effect B. Compton effect c. Theory of relativity D. None of the above |
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327 | Louis de -Broglie is credited for his work on A. Theory of relativity B. Electromagnetic theory c. Matter waves D. Law of distribution of velocities |
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328 | Assertion The photoelectrons produced by a monochromatic light beam incident on a metal surface, have a spread in their kinetic energies. Reason The work function of the metal varies as a function of depth from the surface. A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion C. Assertion is correct but Reason is incorrect D. Assertion is incorrect but Reason is correct |
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329 | In a photo-emissive cell with exciting wavelength ( lambda ), the fastest electron has speed ( v ). If the exciting wavelength is changed to ( 3 lambda / 4 ) the speed of the fastest emitted electron will be : A ( cdot v(3 / 4)^{1 / 2} ) B ( cdot v(4 / 3)^{1 / 2} ) c. less than ( v(4 / 3)^{1 / 2} ) D. greater than ( v(4 / 3)^{1 / 2} ) |
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330 | The peak emission from a black body at a certain temperature occurs at a wavelength of 9000 A. On increasing its temperature, the total radiation emitted is increased 81 times. At the initial temperature when the peak radiation from the black body is incident on a metal surface, it does not cause any photoemission from the surface. After the increase of temperature, the peak radiation from the black body caused photoemission. To bring these photoelectrons to rest, a potential equivalent to the excitation energy between ( n=2 ) and ( n=3 ) Bohr levels of hydrogen atoms is required. Find the work function of the metal. |
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331 | If the energy and momentum of a photon are ( mathrm{E} ) and ( mathrm{p} ) respectively, then the velocity of photon will be This question has multiple correct options A. ( frac{E}{p} ) ( ^{text {В }}left(frac{E}{p}right)^{2} ) ( c cdot E p ) D. ( 3 times 10^{8} mathrm{m} / mathrm{s} ) |
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332 | A proton and ana – particle accelerated through same voltage.The ratio of their de-broglie wavelength will be: A .1: 2 B . ( 2 sqrt{2}: 1 ) c. ( sqrt{2}: 1 ) D. 2: 1 |
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333 | 48. The maximum velocity of electrons emitted from a metal surface is v. What would be the maximum velocity if the frequency of incident light is increased by a factor of 4? (a) 2v (b) > 2v (c) <2v (d) between 2v and 4v. 5 |
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334 | An electron of mass ( m ) and a photon have same energy ( E . ) The ratio of de- Broglie wavelength associated with them is: ( stackrel{mathbf{A}}{_{c}}left(frac{E}{2 m}right)^{frac{1}{2}} ) B. ( quadleft(frac{E}{2 m}right)^{frac{1}{2}} ) ( c cdot(2 m E)^{frac{1}{2}} ) ( stackrel{1}{c}left(frac{2 m}{E}right)^{frac{1}{2}} ) ( (c ) being velocity of light) |
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335 | In a photoelectric experiment, the collector plate is at ( 2.0 mathrm{V} ) with respect to the emitter plate made of copper ( (phi= ) 4.5 ( e V ) ). the emitter is illuminated by a source of monochromatic light of wavelength ( 200 mathrm{nm} ) A. The minimum kinetic energy of the photo electrons reaching the collector is 0 B. The maximum kinetic energy of the photo electrons reaching collector is 3.7 ev. c. If the polarity of the battery is reversed then answer to part A will be o D. If the polarity of the battery is reversed then answer to part B will be 1.7 eV |
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336 | In a photo electric experiment, when intensity of incident light increases: A. photo-current increases B. photo-current decreases C. kinetic energy of emitted photoelectrons increases D. kinetic energy of emitted photoelectrons decreases |
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337 | max 17. Statement 1: When ultraviolet light is incident on a photocell, its stopping potential is V. and the maximum kinetic energy of the photoelectrons is Kmax. When the ultraviolet light is replaced by X-rays, both Vo and K. increase. Statement 2: Photoelectrons are emitted with speeds ranging from zero to a maximum value because of the range of frequencies present in the incident light. (a) Statement 1 is true, statement 2 is true; statement 2 is the correct explanation for statement 1. (b) Statement 1 is true, statement 2 is true; statement 2 is not the correct explanation for statement 1. (c) Statement 1 is false but statement 2 is true. (d) Statement 1 is true but statement 2 is false. (AIEEE 2010) 20 |
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338 | 44. Work function of nickel is 5.01 eV. When ultravi. radiation of wavelength 200 Å is incident on it, elect are emitted. What will be the maximum velocity of emitted electrons ? (a) 3 x 108 m s d (b) 6.46 x 10 ms! (c) 10.36 x 10 m 5-1 (d) 8.54 x 10ºm s-1 |
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339 | In photoelectric effect, the momentum of incident photon of energy ( 3 times 10^{-19} J ) is : ( mathbf{A} cdot 9 times 10^{11} mathrm{kgms}^{-1} ) B. zero c. ( 10^{-27} mathrm{kgms}^{-1} ) D. ( 3 times 10^{-11} mathrm{kgms}^{-1} ) |
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340 | ILLUSTRATION 29.8 An X-ray tube operates at 20 kV. Find the maximum speed of the electrons striking the anode, given the charge of electron is 1.6 x 10-9 coulomb and mass of electron is 9 x 10-31 kg. |
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341 | Davisson Germer experiment explained the wave nature of electrons through A. Electron diffraction B. Electron interference c. Electron scattering D. Failed to explain wave nature of electrons |
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342 | An electron in an atom absorbs radiation of wavelength ( 392 . n . m ) and later on it emits energy in the from of photons of two different wavelengths. If one of the wavelength is 712 n.m. Calculate the other |
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343 | Fill in the blanks: The ( ldots ) tungsten is reduced by coating with barium oxide. A. Normal function B. Force function c. Power function D. Work function |
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344 | The de-Broglie wavelength of electron in ( 3^{r d} ) orbit of ( H e^{+1} ) ion is approximately ( mathbf{A} cdot 2 A^{0} ) B. ( 3 A^{circ} ) c. ( 4 A^{circ} ) D. ( 5 A^{circ} ) |
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345 | The circumstance of first of hydrogen atom is s.Then the Broglie wavelength of electron to that orbit is A ( cdot frac{S}{2} ) в. ( 2 S ) ( c . s ) D. ( 3 S ) |
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346 | The work function of a metal surface is 1 eV. A light of wavelength ( 3000 A^{0} ) is incident on it. The maximum velocity of the photo-electrons is nearly ( mathbf{A} cdot 10^{6} m s^{-1} ) B . ( 10^{4} m s^{-1} ) c. ( 10^{2} m s^{-1} ) D. ( 10 m s^{-1} ) |
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347 | 12. In the following diagram if V, > V, then (Photoelectric current) V2 V, Potential difference (2) n = siz (c) 2 = 2 (b) 2, |
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348 | After absorbing a slowly moving neutron of Mass ( m_{N} ) (momentum ( approx 0 ) ) a nucleus of mass M breaks into two nuclei of masses ( boldsymbol{m}_{1} ) and ( mathbf{5 m}_{mathbf{1}}left(boldsymbol{6} boldsymbol{m}_{mathbf{1}}=right. ) ( left.M+boldsymbol{m}_{N}right) ) respectively. If the de Broglie wavelength of he nucleus with mass ( m_{1} ) is ( lambda, ) the de Broglie wavelength of the nucleus will be. A ( .5 lambda ) B. ( lambda / 5 ) ( c cdot lambda ) D. ( 25 lambda ) |
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349 | Radiation from hydrogen gas excited to first excited state is used for illuminating certain photoelectric plate. When the radiation from some unknown hydrogen-like gas excited to the same level is used to expose the same plate, it is found that the de Broglie wavelength of the fastest photoelectron has decreased 2.3 times. It is given that the energy corresponding to the longest wavelength of the Lyman series of the unknown gas (13.6 eV). Find the work function of the photoelectric plate in eV. ( left[text { take }(2.3)^{2}=5.25right] ) |
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350 | The energy of a photon of light with wavelength ( 5000 A ) is approximately ( 2.5 e V . ) This way the energy of an X-ray photon with wavelength ( 1 A ) would be: A. ( frac{2.5}{(5000)^{2}} e V ) в. ( 2.5 times 5000 ) eV c. ( frac{25}{(5000)^{2}} cdot e V ) D. ( frac{2.5}{5000} e V ) |
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351 | The wavelength of a matter wave is given by A. Heisenberg’s hypothesis B. Bohr’s principle c. Debroglie’s rule D. Newton-laplace rule |
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352 | Threshold wavelength of tungsten is 2300 angstrom. If ultraviolet light of wavelength 1800 angstrom is incident on it, then the maximum kinetic energy of photoelectrons would be? A . 1.5 ev B. 2.5ev c. 3.0 ev D. ( 5.0 mathrm{eV} ) |
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353 | The minimum heat energy required to emit an electron from the surface of a metal is called A. Extracting function B. Work function C. Threshold energy D. None of the above |
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354 | If ( h ) is Plancks constant, the momentum of a photon of wavelength ( 0.01 A^{circ} ) is ( mathbf{A} cdot 10^{-2} h ) B. ( h ) ( c cdot 10^{2} ) D. ( 10^{12} h ) |
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355 | A photon of energy 2.5 eV and wavelength ( ^{prime} lambda^{prime} ) falls on a metal surface and the ejected electrons have maximum velocity ‘ ( v^{prime} . ) If the ( ^{prime} lambda^{prime} ) of the incident light is decreased by ( 20 % ), the maximum velocity of the emitted electrons is doubled. The work function of the metal is : A . 2.6 ev B. 2.23 ev c. 2.5 ev D. 2.29 ev |
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356 | Determine de-Broglie wavelength of an electron having kinetic energy of ( 1.6 times ) ( 10^{-6} ) erg. A ( .12 .42 A^{circ} ) B. ( 12.42 mathrm{cm} ) c. ( 12.42 m ) D. none of these |
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357 | The number of photons falling per second on a completely darkened plate to produce a force of ( 6.62 times 10^{-5} mathrm{N} ) is ‘n’ If the wavelength of the light falling is ( 5 times 10^{-7} m, ) then ( n=_{-1-}—times 10^{22} ) ( left(h=6.62 times 10^{-34} J-sright) ) A . 1 B. 5 ( c .0 .2 ) D. 3.3 |
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358 | How does one explain the emission of electrons from a photosensitive surface with the help of Einstein’s photoelectric equation? | 12 |

359 | Calculate the momentum of particle whose de Broglie wavelength is ( 2^{circ} A ) A ( cdot 3.313 times 10^{-24} g m s^{-1} ) В. ( 3.313 times 10^{-24} k g m s^{-1} ) c. ( 33.13 times 10^{-20} k g m s^{-1} ) D. none of these |
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360 | The work functions of lithium and copper are ( 2.3 e V ) and ( 4.0 e V ) respectively. Out of these, the one which is suitable for the photoelectric cell that works with the visible light is A. lithium B. copper c. both lithium and copper D. neither lithium nor copper. |
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361 | What is photoelectric effect? Explain the effect of increase (i) frequency (ii) intensity of incident radiation on photoelectric current with suitable graphs. |
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362 | The energy of photon of visible light with maximum wavelength in ( e V ) is: ( mathbf{A} cdot mathbf{1} ) в. 1.6 ( c .3 .2 ) D. |
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363 | The energy of an electron of mass ( m ) moving with velocity ( mathrm{V} ) and de-Broglie wavelength ( lambda ) is (‘h’ is Planck’s constant) A ( cdot frac{h}{2 m lambda} ) в. ( frac{h^{2}}{2 m lambda^{2}} ) c. ( frac{h lambda}{2 m} ) D. ( frac{h}{m lambda} ) |
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364 | Find the frequency of photon. A ( cdot 2.71 times 10^{14} mathrm{Hz} ) в. 2.01 ( times 10^{14} mathrm{Hz} ) c. ( 2.5 times 10^{14} H z ) D. 20.1 ( times 10^{14} mathrm{Hz} ) |
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365 | What is the momentum of a photon if the wavelength of X-rays is 1 angstrom? |
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366 | 7. The potential energy of a particle of mass m is given by Eo; OSx51 U(x)= (0; x>1 2, and I are the de Broglie wavelengths of the particle, when 0 SX S1 and x > 1 respectively. If the total energy of particle is 2Eo, the ratio 1 will be 2 (a) 2 (b) 1 (c) V2 |
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367 | A parallel beam of electrons travelling in x-direction falls on a slit of width d. If after passing the slit, an electron acquires momentum ( p_{y} ) in the ( y ) direction, then for a majority of electrons passing through the slit (h is Planck’s constant). ( mathbf{A} cdotleft|P_{y}right| d>h ) ( mathbf{D} cdotleft|P_{y}right| d>h ) |
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368 | A metal is irradiated with light of wavelength ( 600 n m . ) Given that the work function of the metal is ( 1.0 e V ), the de Broglie wavelength of the ejected electron is close to: A ( cdot 6.6 times 10^{-7} mathrm{m} ) в. ( 8.9 times 10^{-11} ) ( _{m} ) c. ( 1.3 times 10^{-9} m ) D. ( 6.6 times 10^{-13} ) и |
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369 | An alpha particle moving with an initia velocity ( (u j) ) enters a region of uniform magnetic field ( B=B k ). the de-Broglie wavelength of the alpha particle. A. Increases to a higher constant value B. Decreases to a lower constant value c. Increases and decreases periodically D. Remains constant |
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370 | ( 10^{-3} W ) of ( 5000 A ) light is directed on a photoelectric cell. If the current in the cell is ( 0.16 mu A ), the percentage of incident photons which produce photoelectrons, is A . ( 40 % ) B . 0.04% c. 20% D. 10% |
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371 | How can photoelectric effect be used to produce electricity | 12 |

372 | ILLUSTRATION 28.3 A source of light of power P is shown in figure. Find the force on the block placed in the path of the light rays. The surface of P watt Light source body on which the light beam is incident is having a reflection coefficient a, = 0.7 and absorption coefficient a, = 0.3. |
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373 | Tungsten has work function ( 4.8 e V . ) We wish to use tungsten as photo-cathode with a 600 nm wavelength. What shall we do? A. Coat tungsten with Cesium B. Oxide coat tungsten c. ( C u_{2} O_{2} ) be coated on tungsten D. None of these |
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374 | An electron gun with its collector at a potential of ( 100 mathrm{V} ) fires out electrons in a spherical bulb containing hydrogen gas at low pressure ( left(sim 10^{-2} mathrm{mm} text { of } mathrm{Hg} text { ). } mathrm{A}right. ) magnetic field of ( 2.83 times 10^{4} T ) curves the path of the electrons in a circular orbit of radius 12.0 cm. (The path can be viewed because the gas ions in the path focus the beam by attracting electrons, and emitting light by electron capture; this method is known as the fine beam tube method.) Determine e/m from the data. |
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375 | The de-Broglie wavelength of a proton and alpha particle is same, the ratio of their velocities is : A . 1: 2 B. 2: ( c cdot 1: 4 ) D. 4: |
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376 | Protons are accelerated from rest by a potential difference ( 4 mathrm{kV} ) and strike a metal target. If a proton produces one photon on impact of minimum wavelength ( lambda_{1} ) and similarly an electron accelerated to ( 4 mathrm{kV} ) strikes the target and produces a minimum wavelength ( lambda_{2} ) then A ( cdot lambda_{1}=lambda_{2} ) B. ( lambda_{1}>lambda_{2} ) ( c cdot lambda_{1}<lambda_{2} ) D. no such relation can be established |
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377 | Consider a hypothetical hydrogen like atom. The wavelength in ( A ) for the spectral lines for transition from ( boldsymbol{n}=boldsymbol{p} ) ( operatorname{ton}=1 ) are given by- ( lambda=frac{1500}{p^{2}-1} ) Where ( boldsymbol{p}=mathbf{2}, mathbf{3}, mathbf{4}, ) (given ( boldsymbol{h} boldsymbol{c}= ) ( 12400 e V / A) ) This question has multiple correct options A. The wavelength of the least energetic and the most energetic photons in this series is 2000 A, 1500 A B. Difference between energies of fourth and this orbit is ( 0.40 mathrm{eV} ) C. Energy of second orbit is 6.2 eV D. The ionization potential of this element is ( 8.27 V ) |
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378 | Maximum kinetic energy of the emitted photoelectrons depends upon A. Intensity of incident light B. Frequency of incident light c. Total number of photons of incident light D. Both (2) and (3) |
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379 | The ratio of wavelengths of electron waves in two orbits is ( 3: 5 . ) The ratio of kinetic energy of electrons will be: ( mathbf{A} cdot 25: 9 ) B. 5: 3 ( mathbf{c} cdot 9: 25 ) D. 3: 5 |
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380 | A plot of the kinetic energy ( left(1 / 2 m v^{2}right) ) of ejected electrons as a function of the frequency (v) of incident radiation for four alkali metals ( left(M_{1}, M_{2}, M_{3}, M_{4}right) ) is shown below: The alkali metals ( M_{1}, M_{2}, M_{3} ) and ( M_{4} ) |
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381 | A heavy nucleus at rest breaks into two fragments which fly off with velocities in the ratio ( 8: 1 . ) the ratio of de-broglie wavelengths of fragments are A . 1: 2 B. 1: 8 c. 4: 1 D. None of these |
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382 | 42. The KE of the photoelectrons is E when the incident wavelength is 1/2. The KE becomes 2E when the incident wavelength is N3. The work function of the metal is (a) hcl 2 (b) 2hc/2 (c) 3hc/a (d) hc/32 |
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383 | The work function of a certain metal is 4.2 eV. Which among the wavelengths ( 390 mathrm{nm}, 440 mathrm{nm}, 550 mathrm{nm} ) and ( 70 mathrm{nm} ) will this metal give photoelectric emission? A. 390 nm only B. 390 nm, 440 nm only ( mathrm{c} .390 mathrm{nm}, 440 mathrm{nm} ) and ( 550 mathrm{nm} ) D. None of them |
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384 | The wavelength of an electron: This question has multiple correct options A. is equal to that of light B. remains constant with velocity C . decreases with an increasing velocity D. increases with an decreasing velocity |
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385 | A student prepares a ( 0.10 M ) CoCl ( _{2} ) solution and determines the absorbance of the solution at various wavelengths using a spectrophotometer. A graph of the results is shown below. Identify the optional wavelength for |
12 |

386 | 40. When a centimeter thick surface is illuminated with lishe of wavelength 2, the stopping potential is V. When same surface is illuminated by light of wavelength 22 the stopping potential is V/3. Threshold wavelength for the metallic surface is (a) 41/3 (b) 42 (c) 62 (d) 82/3 |
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387 | A photon of energy 10.2 eV corresponds to light of wavelength ( lambda_{0} . ) Due to an electron transition from ( x=2 ) to ( x=1 ) in a hydrogen atom, light of wavelength A is emitted. If we take into account the recoil of the atom when the photon is emitted, then : ( A cdot lambdalambda_{0} ) c. ( lambda=lambda_{0} ) D. None of these |
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388 | 49. In a photocell, with excitation wavelength 2, the faster electron has speed v. If the excitation wavelength is changed to 3N4, the speed of the fastest electron will be (a) V(3/4)1/2 (b) v(4/3)1/2 (c) less than v(4/3)/2 (d) greater than v(4/3)1/2 |
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389 | A radio transmitter operates at a frequency of ( 880 mathrm{kHz} ) and power of 10 kW. The number of photons emitted per second is : ( mathbf{A} cdot 13.27 times 10^{4} ) B. ( 13.27 times 10^{3} ) c. ( 1327 times 10^{34} ) D. ( 1.71 times 10^{31} ) |
12 |

390 | Mention any two types of electron emission | 12 |

391 | 43. The threshold frequency for certain metal is v. When liche of frequency 2v, is incident on it, the maximum velo of photoelectrons is 4 x 100 m s. If the freque incident radiation is increased to 5 Vo, then the maximum velocity of photoelectrons will be (a) 4/5 x 10 m s-1 (b) 2 x 10ºm s-1 (c) 8 x 10 m s-1 (d) 2 x 10’m s-1 |
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392 | If ( E_{1}, E_{2} ) and ( E_{3} ) are the kinetic energies of a proton, ( alpha ) -particle and deuteron respectively, which all have the same wavelength, then A ( cdot E_{1}>E_{2}>E_{3} ) в. ( E_{1}>E_{3}>E_{2} ) c. ( E_{3}>E_{2}>E_{1} ) D. ( E_{3}>E_{1}>E_{2} ) |
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393 | After absorbing a slowly moving neutron of mass ( m_{N} ) (momentum ( sim 0 ) ) a nucleus of mass ( M ) breaks into two nuclei of masses ( m_{1} ) and ( mathbf{5} boldsymbol{m}_{1}left(boldsymbol{6} boldsymbol{m}_{1}=boldsymbol{M}+boldsymbol{m}_{N}right) ) respectively. If the de-Broglie wavelength of the nucleus with mass ( m_{1} ) is ( lambda ), the de Broglie wavelength of the other nucleus will be: ( A cdot lambda ) в. ( 25 lambda ) ( c cdot 5 lambda ) D. ( lambda / 5 ) |
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394 | A photon of energy ( mathrm{E}_{1} ) incident on a surface liberates electrons whose energy is equal to the work function ( mathbf{W} ) of the metal. When a photon of energy 2 is incident on the same surface, energy of the emitted electrons is ( 3 mathrm{W} ) The ratio ( mathrm{E}_{1}: mathrm{E}_{2} ) is A . 1: 2 B. 2: c. 1: 3 D. 3: |
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395 | Light described at a place by the equation ( boldsymbol{E}=(mathbf{1 0 0} boldsymbol{V} / boldsymbol{M}) times[sin (mathbf{5} times ) ( left.mathbf{1 0}^{mathbf{1 5}} boldsymbol{s}^{-mathbf{1}}right) boldsymbol{t}+boldsymbol{operatorname { s i n }}left(boldsymbol{8} times mathbf{1 0}^{mathbf{1 5}} boldsymbol{s}^{-mathbf{1}}right) boldsymbol{t} ) Falls on a metal surface having work function 2.0 e.V Calculate the maximum kinetic energy of the photoelectrons A . 3.27 ev B. 5 ev c. 1.27 ev D. 2.5 ev |
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396 | The ratio of wavelengths of photons emitted when hydrogen atom de-excites from third excited state to second excited state an then de-excites form seconds excited state to first excited state is A ( cdot frac{7}{20} ) в. ( frac{20}{7} ) ( c .5 ) D. 20 |
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397 | The ratio of the deBroglie wave length for the electron and proton moving with same velocity is: ( left[m_{p}-text { mass of propton, } m_{e}- ) mass of right. electron] ( mathbf{A} cdot m_{p}: m_{e} ) в. ( m_{p}^{2}: m_{e}^{2} ) ( mathbf{c} cdot m_{e}: m_{p} ) D. ( m_{e}^{2}: m_{p}^{2} ) |
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398 | Which of these particles having the same kinetic energy has the largest de Broglie wavelength? A. Electron B. Alpha particle c. Proton D. Neutron |
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399 | The de Broglie wavelength associated with an electron of energy 500 ev is given by (take ( boldsymbol{h}=mathbf{6 . 6 3} times mathbf{1 0}^{-mathbf{3 4} mathbf{J}} boldsymbol{s}, boldsymbol{m}=mathbf{9 . 1 1} times ) ( left.10^{-31} k gright) ) A ( cdot 0.28 A^{0} ) B . 1.410 ( A^{circ} ) ( c cdot 0.66 A^{0} ) D. 0.55 ( A^{circ} ) |
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400 | Davisson and Thomson shared the Nobel Prize for their experimental discovery of diffraction of electrons by crystals. True ( =1, ) false ( =0 ) |
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401 | Find the maximum potential a ( boldsymbol{C u} ) ball (isolated) can have when irradiated with a wavelength ( lambda=140 n m ) ( left[phi_{C u}=4.47 mathrm{eV}right] ) A . ( 4.47 V ) B. 8.86 ( V ) c. ( 13.33 V ) D. 4.39 ( V ) |
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402 | The threshold wavelength for emission of photoelectrons from a metal surface is ( 6 times 10^{-7} mathrm{m} . ) The work function of the material of the metal surface is : A ( cdot 3.33 times 10^{-19} mathrm{J} ) J. ( 3.33 times 10^{-19} ) В ( cdot 6.67 times 10^{-19} mathrm{J} ) С. ( 1.23 times 10^{-19} mathrm{J} ) J ( 5 times 10^{-1.2} ) D. ( 2.37 times 10^{-19} mathrm{J} ) |
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403 | The wavelength ( lambda_{e} ) of an electron and ( lambda_{p} ) of a photon of same energy ( boldsymbol{E} ) are related by: ( A cdot lambda_{p} propto lambda_{e} ) B. ( lambda_{p} propto sqrt{lambda_{e}} ) c. ( lambda_{p} propto frac{1}{sqrt{lambda_{e}}} ) D. ( lambda_{p} propto lambda_{e}^{2} ) |
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404 | An electron is moving in ( 2^{n d} ) excited orbit of H-atom Radius of orbit in terms of de-Broglie wavelength ( lambda ) of electron can be given as ( A cdot frac{lambda}{pi} ) в. ( frac{2 lambda}{pi} ) c. ( frac{3 lambda}{2 pi} ) D. ( frac{lambda}{2 pi} ) |
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405 | When an electron falls from ( 2^{n d} ) energy level to ground state then which of the following will produce shortest wavelength? A ( cdot B e^{3+} ) ion B. ( D ) -atom c. ( H- ) atom D. ( H e^{+} ) ion |
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406 | The circumference of the second Bohr orbit of electron in the hydrogen atom is ( 600 n m . ) Calculate the potential difference to which the electron has to be subjected so that the electron stops. The electron had the de Broglie wavelength corresponding to the circumference. |
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407 | 13. Two electrons are moving with same speed v. One electro enters a region of uniform electric field while the other enters a region of uniform magnetic field, then after some time de Broglie wavelengths of two are 2, and 2 respectively. Now, (a) 11 = , (b) 2,> (c) 2,< (d) 2, can be greater than or less than , |
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408 | (c) 2X 10 (0) 1.07 10 6. An electron of mass m, and a proton of mass m, are accelerated through the same potential difference. The ratio of the de Broglie wavelength associated with an electron to that associated with proton is (a) 1 (b) melme (c) m/m (d) m ime |
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409 | Assertion In photoelectron emission the velocity of electron ejected from near the surface is larger than that coming from interior of metal. Reason The velocity of ejected electron will be zero A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion c. Assertion is correct but Reason is incorrect D. If Assertion is incorrect but Reason is correct |
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410 | Define the following in photoelectric effect phenomenon: (a) (i) Work function (ii) Stopping potential (cut-off potential) (b) Calculate energy of photon of wavelength ( 3.31 A ) |
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411 | What is the wavelength of light emitted when the electron in a hydrogen atom undergoes a transition from an energy level with ( n=4 ) to an energy level with ( boldsymbol{n}=mathbf{2} ? ) A ( .5654 A^{circ} ) B. ( 3852 A^{circ} ) ( mathbf{c} cdot 4920 A^{circ} ) D. ( 4852 A^{circ} ) |
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412 | De Broglie wavelength of neutrons in thermal equilibrium is (given ( boldsymbol{m}_{boldsymbol{n}}= ) ( left.1.6 times 10^{-27} k gright) ) A ( cdot 30.8 / sqrt{T}_{A}^{circ} ) B ( cdot 3.08 / sqrt{T}_{A}^{o} ) c. ( 0.308 / sqrt{T}_{A}^{circ} ) D ( cdot 0.0308 / sqrt{T}^{circ} ) |
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413 | 31. A proton when accelerated through a potential difference of V volt has a wavelength 2 associated with it. An Ol-particle in order to have the same 2 must be accelerated through a potential difference of (a) V volt (b) 4V volt (c) 2V volt (d) (V/8) volt |
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414 | The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photo electron emission from this substance is approximately: A. ( 540 mathrm{nm} ) B. 440 nm ( c .310 mathrm{nm} ) D. 220 nm |
12 |

415 | 21. Statement 1: Davisson-Germer experiment established the wave nature of electrons. Statement 2: If electrons have wave nature, they can interfere and show diffraction. (a) Statement 1 is false but statement 2 is true. (b) Statement 1 is true but statement 2 is false (c) Statement 1 is true, statement 2 is true, statement 2 is the correct explanation for statement 1 (d) Statement 1 is true, statement 2 is true, statement 2 is not the correct explanation of statement 1 (AIEEE 2012) |
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416 | If the momentum of an electron is changed by ( p_{m}, ) then the de Broglie wavelength associated with it increased by ( 0.5 % ). The initial momentum of electron will be A ( cdot p_{m} / 200 ) в. ( p_{m} / 100 ) c. ( 201 p_{m} ) D. ( 100 p_{m} ) |
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417 | The work function of the following metals is given: ( N a=2.75 e V, K= ) ( mathbf{2 . 3} e V, M o=4.17 e V ) and ( N i= ) ( 5.15 e V . ) Which of these metals will not undergo photoelectric emission for radiation of wavelength ( 3300 A ) from a laser source placed 1 m away from these metals? What happens if the laser source is brought closer and placed ( 50 mathrm{cm} ) away? |
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418 | A particle of mass ( mathrm{M} ) at rest decays into two particles of masses ( m_{1} ) and ( m_{2} ) having non zero velocities. The ratio of the de Broglie wavelengths of the particles, ( lambda_{1} / lambda_{2} ) is? |
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419 | 5. The ratio of de Broglie wavelength of a a-particle to that of a proton being subjected to the same magnetic field so that the radii of their paths are equal to each other assuming the field induction vector B is perpendicular to the velocity vectors of the a-particle and the proton is (a) 1 (b) (d) 2 |
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420 | 8. If no stands for mid-wavelength in the visible region, the de Broglie wavelength for 100 V electrons is nearest to (a) 20/5 (b) 20/50 (c) 20/500 (d) 20/5000 L L . 11.cc |
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421 | 68. The kinetic energy of a particle is equal to the enerov a photon. The particle moves at 5% of the speed of light The ratio of the photon wavelength to the de Broglie wavelength of the particle is [No need to use relativistic formula for the particle. (a) 40 (b) 4 (c) 2 (d) 80 |
12 |

422 | Wavelength associated with an electron having kinetic energy ( 3 times 10^{-25} J ) is ( x times 10^{-7} ) m. What is the value of ( x ? ) ( A cdot 9 ) B. 4 ( c .5 ) D. 6 |
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423 | Work function of a metal is the: A. Energy required by an electron to get absorbed in the metal surface. B. Minimum energy required by an electron to escape from the metal surface. C. Energy required by an electron to be retained in the metal surface. D. Maximum energy required by an electron to escape from the metal surface. |
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424 | A modern 200 W sodium street lamp emits yellow light of wavelength ( 0.6 mu m ) Assuming it to be ( 25 % ) efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is : A ( cdot 62 times 10^{20} ) B . ( 3 times 10^{19} ) c. ( 1.5 times 10^{20} ) D. ( 6 times 10^{18} ) |
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425 | 9. In a photocell, bichromatic rays of light of wavelength 2475 Å and 6000 Å are incident on cathode whose work function is 4.8 eV. If a uniform magnetic field of 3 x 10-5 tesla exists parallel to the plate, the radius of the path describe by the photoelectron will be (mass of electron = 9 x 10-31 kg) (a) 1 cm (b) 5 cm (c) 10 cm (d) 25 cm |
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426 | The de Broglie wavelength of a tennis ball of mass 60 g moving with a velocity of ( 10 mathrm{m} / mathrm{sec} ) is approximately: A. ( 10^{-33} mathrm{m} ) . В . ( 10^{-31} mathrm{m} ) c. ( 10^{-16} mathrm{m} ) . D. ( 10^{-25} mathrm{m} ) |
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427 | In an experiment on photoelectric effect, Light of wavelength 800 nm (less than threshold wavelength) is incident on a cesium plate at the rate of ( 5.0 mathrm{W} ) The potential of the collector plate is made sufficiently positive with respect on the emitter so that the current reaches its saturation value. Assuming that on the average one of every ( 10^{6} ) photons is able to eject a photoelectron, find the photo current in the circuit. |
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428 | The wavelength associated with 1 Me ( V ) proton is A. ( 28.6 p m ) B. 2.86 ( p m ) c. ( 2.86 mathrm{fm} ) D. 28.6 ( f m ) |
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429 | When a surface is irradiated with light of wavelength ( 4950, ) a photocurrent appears which vanishes if a retarding potential greater than ( 0.6 ~ V ) is applied across the phototube. When different source of light is used, it is found that the critical retarding potential is changed to ( 1.1 mathrm{V} ). Find the work function of the emitted surface and the wavelength of the second source. |
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430 | The important conclusion given by Millikan’s experiment about the charge is A. Charge is never quantised B. Charge has no definite value c. Charge is quantised D. Charge on an oil drop always increases |
12 |

431 | De-Broglie wavelength depends on A. Mass of the particle B. Size of the particle C. Material of the particle D. Shape of the particle |
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432 | Which of the following particles neutron, proton,electron and deuteron has the lowest energy if all have the same de Broglie wavelength: A. neutron B. proton c. electron D. deuteron |
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433 | Two large vertical and parallel metal plates having a separation of ( 1 mathrm{cm} ) are connected to a ( D C ) voltage source of potential difference ( X . ) A proton is released at rest midway between the two plates. It is found to move at ( 45^{circ} ) to the vertical JUST after release. Then ( boldsymbol{X} ) is nearly A. ( 1 times 10^{-5} V ) В . ( 1 times 10^{-7} V ) c. ( 1 times 10^{-9} V ) D. ( 1 times 10^{-10} V ) |
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434 | The de-Broglie wavelength of an electron traveling with speed equal to ( 1 % ) of the speed of light: ( A cdot 400 mathrm{pm} ) в. 120 pm ( c .242 mathrm{pm} ) D. 375 pm |
12 |

435 | Write Einstein’s photo electric equation. | 12 |

436 | If kinetic energy of an electron is reduced by ( (1 / 9) ) then how many times its de Broglie wavelength will increase? A . 3 B. 4 c. 5 D. 6 |
12 |

437 | Light of two different frequencies whose protons have energies ( 1 e V ) and ( 2.5 e V ) respectively, successively illuminate a metallic surface whose work function is ( 0.5 e V . ) Ratio of maximum speeds of emitted electrons will be A .1: 5 B. 1: 4 c. 1: 2 D. 1: 1 |
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438 | ( x- ) rays of wavelength ( lambda ) falls on a photosensitive surface emitting electrons.Assuming that the work function of the surface can be neglected, prove that the de Broglie wavelength of electrons emitted will be ( sqrt{frac{h lambda}{2 m c}} ) |
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439 | Name the unit in which work function of a metal is generally expressed. How is it related to the S.I. unit joule? ( mathbf{A} cdot e V, 1 e V=1.6 times 10^{9} J ) B . ( e V, 1 e V=1.6 times 10^{-9} J ) c. ( e V, 1 e V=1.6 times 10^{-19} J ) D. ( e V, 1 e V=1.6 times 10^{19} J ) |
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440 | A photon of frequency n causes photoelectric emission from a surface with threshold frequency ( v_{o} ). the de Broglie wavelength ( lambda ) of the photoelectron emitted is given as: A ( cdot Delta n=frac{h}{2 m lambda} ) B. ( Delta n=frac{h}{lambda} ) ( ^{mathrm{C}}left[frac{1}{v_{o}}-frac{1}{v}right]=frac{m c^{2}}{h} ) D. ( lambda=sqrt{frac{h}{2 m Delta n}} ) |
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441 | A charged dust particle of radius ( 5 times ) ( 10^{-7} mathrm{m} ) is located in a horizontal electric field having an intensity of ( 6.28 times 10^{5} v / m . ) The surrounding medium is air with coefficient of viscosity ( boldsymbol{eta}=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{5}} mathbf{N S} / mathbf{m}^{2} . ) If the particle has a charge of ( 7.2 times 10^{-15} ) then it moves with a uniform horizontal speed of A . 10 в. 20 ( c .30 ) D. 40 |
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442 | Radiations of two different frequencies whose photon energies are ( 3.4 e V ) and ( 8.2 e V ) successive illuminate a metal surface whose work function is ( 1.8 e V ) The ratio of the maximum speeds of the emitted electrons will be: A . 1: 1 B. 1: 2 ( c cdot 1: 3 ) D. 1: 4 |
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443 | A particle is dropped from a height ‘ ( boldsymbol{H} ) ‘. The de Broglie wavelength of the particle depends on height as A. ( H ) B. ( H^{-1 / 2} ) ( mathrm{c} cdot H^{0} ) D. ( H^{1 / 2} ) |
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444 | OUPS 51. When a certain metallic surface is illuminated with monochromatic light of wavelength 2, the stopping potential for photoelectric current is 3V, and when the same surface is illuminated with light of wavelength 22, the stopping potential is V. The threshold wavelength of this surface for photoelectric effect is (a) 62 (b) 41/3 (c) 42 (d) 82 |
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445 | If velocity of a particle is 3 times of that of electron and ratio of de brogile wavelength of particle to that of electron is ( 1.814 times 10^{-4} . ) The particle will be:- A. Neutron B. Deutron c. Alpha D. Tritium |
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446 | Find the de Broglie wavelength of electrons moving with a speed of ( 7 times ) ( 10^{6} m s^{-1} ) |
12 |

447 | Find the de-Broglie wavelength of an electron with kinetic energy of ( 120 e V ) ( mathbf{A} cdot 95 p m ) в. ( 102 mathrm{pm} ) c. 112 pm D. ( 124 mathrm{pm} ) |
12 |

448 | Which of the following expression gives the de-Broglie relationship? A ( cdot p=frac{h}{m v} ) B. ( lambda=frac{h}{m v} ) c. ( lambda=frac{h}{m p} ) D ( cdot lambda m=frac{v}{p} ) |
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449 | An ( alpha ) particle moves in circular path of radius ( 0.83 mathrm{cm} . ) In the presence of a magnetic field of ( 0.25 W b / m^{2} . ) Find the De Broglie wavelength associated with the particle |
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450 | Let ( p ) and ( E ) denote the linear momentum and the energy of a photon. For another photon of smaller wavelength (in same medium) A. Both ( p ) and ( E ) increase B. ( p ) increases and ( E ) decreases c. ( p ) decreases and ( E ) increases D. Both ( p ) and ( E ) decrease |
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451 | Light of wavelength ( 5000 dot{A} ) and intensity ( 3.96 times 10^{-3} W / c m^{2} ) is incident on the surface of a photosensitive material. If 1 percent of incident photons only emit photoelectrons, then the number of electrons emitted per unit area from the surface will be A ( cdot 10^{16} ) B. ( 10^{18} ) ( c cdot 10^{20} ) D. ( 10^{2} ) |
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