# Physics class12 Chapter 11 RADIATION AND DUAL NATURE OF MATTER

Q.1. Electron volt (eV) is the measure of

(A) charge

(B) potential difference

(C) current

(D) energy

Ans :- (D)

Q.2. Dimension of plank constant is

(A) ML²T⁻¹

(B) ML²T⁻²

(C) MLT⁻¹

(D) MLT⁻²

Ans :- (A)

Q.3. On the basis of photo electric effect, light is

(A)  Wave

(B) Particle

(C) Both

(D) None of these

Ans :- (B)

Q.4. The energy of emitted photo electron depends up on

(A) Intensity of light

(B) Wave length of light

(C) Work – function of metal

(D) None of these

Ans :- (B)

Q.5. The number of Photons of frequency 10¹⁴ Hz in radiation of 6.62 J will be

(A) 10¹⁰

(B) 10¹⁵

(C) 10²⁰

(D) 10²⁵

Ans :- (C)

Q.6. Dimensional formula of the Planck’s constant is

(A) [ML²T⁻¹]

(B) [ML²T⁻²]

(C) [MLT⁻¹]

(D) none of these

Ans :- (A)

Q.7. de Broglie relation is

(A) λ = h/P

(B) λ = P/h

(C) λ = h × P

(D) λ = h²/ P²

Ans :- (A)

Q.8. The discovery of photoelectric effect is first observed by

(A) Einstein

(B) Heinrich Hertz

(C) J.J Thomson

(D) none of these

Ans :- (B)

Q.9. In compton effect, the value of compton shift is maximum for photon – scattering angle of

(A) 0⁰

(B) 45⁰

(C) 90⁰

(D) 180⁰

Ans :- (D)

Q.10. When a photon stimulates the emission of another photon, the two photons have

(A) same energy

(B) same direction

(C) same wavelength

(D) all of above

Ans:- (D)

Q.11. The energy (E) of photon is

(A) hv

(B) hv/c

(C) 1/2 mv

(D) h/p

Ans :- (A)

Q.12. The SI unit of Planck’s constant is

(A) Js

(B) Ws

(C) Js⁻¹

(D) Js⁻²

Ans :- (A)

Q.13. Work function is measured in

(A) electron – volt

(B) watt

(C) volt

(D) none of these

Ans :- (A)

Q.14. What is the minimum value of compton shift ?

(A) zero

(B) 2h/m₀C

(C) m₀C/2h

(D) none of these

Ans :- (A)

Q.15. What is the maximum value of compton shift ?

(A) zero

(B) 2h/m₀C

(C) m₀C/2h

(D) none of these

Ans :- (B)

Q.16. The de Broglie wavelength of a particle of K.E. ‘K’ is λ. What would be the wavelength of the particle if its K.E. were K/4 ?

(A) λ/2

(B) λ/4

(C) λ

(D) 2λ

Ans :- (D)

Q.17. An electron is accelerate through a potential difference of 300V. What is the wavelength of the electron ?

(A) 71 A

(B) 7.1 A

(C) 0.71 A

(D) none of these

Ans :- (C)

Q.18. What is the frequency associated with a photon of energy 3.3×10⁻¹⁰ J ?

(A) 5×10²³ Hz

(B) 5×10²² Hz

(C) 5×10¹¹ Hz

(D) none of these

Ans :- (A)

Q.19. λ is proportional to

(A) 1/E for both photon and particles

(B) 1/E for photon and 1/√E for particles

(C) 1/√E for both photon and particles

(D) none of these

Ans :- (B)

Q.20. When ultraviolet ray are incident on a metal plate, photo-electric effect does not occur. It occurs by incidence of

(A) infrared rays

(B) X-rays

(C) radiowaves

(D) microwave

Ans :- (B)

Q.21. The de Broglie wavelength of a moving particle becomes larger if its

(A) mass is increased

(B) momentum is reduced

(C) momentum is increased

(D) velocity is increased

Ans :- (B)

Q.22. If the intensity of incident radiation is doubled, what changes occur in the photoelectric current ?

(A) photoelectric current is doubled

(B) photo electric current is halved

(C) both ‘A’ and ‘B’

(D) none of these

Ans :- (A)

Q.23. If particles are moving with same velocity, then which has maximum de Broglie wavelength ?

(A) proton

(B) α-particle

(C) neutron

(D) β-particle

Ans :- (D)

Q.24. If an electron be accelerated from rest by a potential difference of 1 volt, its kinetic energy will be

(A) 1.6×10⁻¹⁹ joule

(B) 7.6×10⁻¹⁹ joule

(C) 1.6×10⁻¹³ joule

(D) none of these

Ans :- (A)

Q.25. A particle is dropped from a height H . The de Broglie wavelength of the particle as a function of height is proportional to

(A) H

(B) H¹/²

(C) H⁰

(D) H⁻¹/²

Ans :- (D)

Q.26. Photo cell is converted

(A) mechanical energy into electrical energy

(B) electrical energy into light energy

(C) light energy into electrical energy

(D) electrical energy into mechanical energy

Ans :- (C)

Q.27. The work function of metal A is twice the work function of metal B. The ratio of threshold wavelength for metal A to that of metal B is

(A) 1:2

(B) 2:1

(C) 1:4

(D) 1:1

Ans :- (A)

Q.28. The de Broglie wavelength associated with an electron accelerated through a potential difference ‘V’ is λ . What will be its wavelength when the accelerating potential difference is increased to 4V?

(A) λ

(B) 2λ

(C) λ/2

(D) none of these

Ans :- (C)

Q.29. Photoelectric effect reveals the

(A) wave nature of radiation

(B) particle nature of radiation

(C) both ‘A’ and ‘B’

(D) e.m. nature of radiation

Ans :- (B)

Q.30. An electron and an α-particle have the same de Broglie wavelength associated with them. What is the ratio of the kinetic energy?

(A) me:mₐ

(B) 1:1

(C) 2me:mₐ

(D) mₐ:me

Ans :- (D)

Q.31. What is the momentum of a photon of frequency ν

(A) hν

(B) C/hν

(C) h/C

(D) none of these

Ans :- (A)

Q.32. The energy of a photon of green light of wavelenght 5500 A is

(A) 2.20 eV

(B) 2.0 eV

(C) 2.25 eV

(D) 2.3 eV

Ans :- (C)

Q.33. If the maximum kinetic energy of electron emitted in a photocell is 5 eV, what is the stopping potential ?

(A) 10 V

(B) 0.5 V

(C) 15 V

(D) 5 V

Ans :- (D)

Q.34. X-rays are made up of

(A) negatively charged particles

(B) positively charged particles

(C) electromagnetic radiations

(D) neutrons

Ans :- (C)

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