Class XII Physics Important Qs on Dual Nature of Radiation and Matter

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Question 1

A particle is dropped from a height ‘H’. The de’Broglie wavelength of the particle depends on height as

• AH
• BH⁰
• CH^1/2
• DH^-1/2

Question 2

In Thomson experiment of finding for electrons, beam of electrons is replaced by that of muons) particle with same charge as of electrons but mass 208 times that of electrons). No deflection condition in this case satisfied, if

• AB is increased 208 times
• BE is increased 208 times
• CB is increased 14.4 times
• DNone of the above

Question 3

In Davisson and Germer experiment, if the intensity of scattered beam of electrons is found to be maximum at 50˚ angle of scattering then at what would be the accelerating potential?

• A55 V
• B54 V
• C50 V
• D51 V

Question 4

Two sources A and B have same power. The wavelength of radiation of A is λ_a and that λ_b. The number of photons emitted per second by A and B are n_a and n_b respectively, then -

• Aλ_e> λ_b
• Bif λ_a > λ_b, n_a< n_b
• Cif λ_a < λ_b, n_a< n_b
• Dif λ_a > λ_b, n_a= n_b

Question 5

The collector plate in an experiment on photoelectric effect is kept vertically above the emitter plate. Light source is put on an a saturation photocurrent is recorded. An electric field is switched on which has a vertically downward direction -

• Athe photocurrent will increase
• Bthe kinetic energy of the electrons reaching collector will increase
• Cthe stopping potential will decrease
• Dthe threshold wavelength will increase

Question 6

From the figure describing photoelectric effect we may infer correctly that -

• ANa and Al both have the same threshold frequency
• BMaximum kinetic energy for both the metals depend linearly on the frequency
• CThe stopping potentials are different for Na and Al for the same change in frequency
• DAl is a better photo sensitive material than Na

Question 7

Silver has a work function fo 4.7 eV. When ultraviolet light of wavelength 100 nm is incident upon it, a potential of 7.7 volt is required to stop the photoelectrons from reaching the collector plate. The potential required to stop photo electrons when light of wavelength 200 nm is incident upon silver is-

• A1.5 V
• B1.85 V
• C1.95 V
• D2.37 V

Question 8

When a certain metal surface is illuminated with light of frequency v, the stopping potential for photoelectric current is V₀. When the same surface is illuminated by light of frequency the stopping potential is (V₀/4).The threshold frequency for photoelectric emission is

• A
• B
• C
• D

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