CBSE Class 12 Physics Dual Nature of Radiation and Matter MCQs Set 04

Question. Which of the following waves can produce photo electric effect
(a) UV radiation
(b) Infrared radiation
(c) Radio waves
(d) Microwaves

Answer: A

Question. Work function of alkali metals is
(a) less than zero
(b) just equal to other metals
(c) greater than other metals
(d) quite less than other metals

Answer: D

Question. Packet of energy are called
(a) electron
(b) quanta
(c) frequency
(d) neutron

Answer: B

Question. One quantum of radiation is called
(a) meter
(b) meson
(c) photon
(d) quark

Answer: C

Question. Energy associated with each photon
(a) hc
(b) mc
(c) hv
(d) hk

Answer: C

Question. One quantum of radiation is called
(a) meter
(b) meson
(c) photon
(d) quark

Answer: C

Question. If an electron and proton are propagating in the form of waves having the same λ , it implies that they have the same
(a) energy
(b) momentum
(c) velocity
(d) angular momentum

Answer: B

Question. Moving with the same velocity , which of the following has the longest de Broglie wavelength?
(a) ᵦ -particle
(b) α -particle
(c) proton
(d) neutron.

Answer: B

Question.The dual nature of light is exhibited by
(a) diffraction and photo electric effect
(b) photoelectric effect
(c) refraction and interference
(d) diffraction and reflection.

Answer: A

Question. If the momentum of a particle is doubled , then its de-Broglie wavelength will
(a) remain unchanged
(b) become four times
(c) become two times
(d) become half

Answer: D

Question. Velocity of a body of mass m, having de-Broglie wavelength λ , is given by relation
(a) v = λ h/m
(b) v = λm/h
(c) v = λ/hm
(d) v = h/ λm

Answer: D

Assertion (A) & Reason(R)

Question. Directions: In each of the following questions, a statement of Assertion (a) is given followed by a corresponding statement of Reason (R) just below it. Of the statements, mark the correct answer as:
(a) If both assertion and reason are true and reason is the correct explanation of assertion
(b) If both
assertion and reason are true but reason is not the correct explanation of assertion
(c) If assertion is true and reason is false
(d) If both assertion and reason are false

1. Assertion: A photon has no rest mass , yet it carries definite momentum.
Reason: Momentum of photon is due to its energy and hence its equivalent mass.
(a) A
(b) B
(c) C
(d) D

Answer: a

Question. Assertion: Mass of moving photon varies inversely as the wavelength.
Reason: Energy of the particle = mass x (speed of light)2
(a) A
(b) B
(c) C
(d) D

Answer: a

Question. 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) A
(b) B
(c) C
(d) D

Answer: c

Question. Assertion: A photocell is called an electric eye.
Reason. When light is incident on some semiconductor, its electrical resistance is reduced .
(a) A
(b) B
(c) C
(d) D

Answer: c

Question. Assertion: The de Broglie equation has significance for any microscopic or submicroscopic particle.
Reason: The de Broglie wavelength is inversely proportional to the mass of the object if velocity is constant.
(a) A
(b) B
(c) C
(d) D

Answer: a

Question. Assertion : A particle of mass M at rest decay into particles of masses m1 and m2,having nonzero velocities will have ratio of de-Broglie wavelengths unity.
Reason. Here we cannot apply conservation of linear momentum.
(a) A
(b) B
(c) C
(d) D

Answer: a

Question. Assertion: Photoelectric effect demonstrates the wave nature of light.
Reason. The number of photoelectrons is proportional to the frequency of light.
(a) A
(b) B
(c) C
(d) D

Answer: d

Question. Assertion: When acertain wavelength of light falls on a metal surface it ejects electron.
Reason. Light has wave nature.
(a) A
(b) B
(c) C
(d) D

Answer: b

Question. Assertion: As work function of a material increases by some mechanism, it requires greater energy to excite the electrons from its surface.
Reason. A plot of stopping potential (V2) versus frequency (v) for different materials,has greater slope for metals with greater work functions.
(a) A
(b) B
(c) C
(d) D
Answer: c

Question. Assertion : Light of frequency 1.5 times the threshold frequency is incident on photosensitive material. If the frequency is halved and intensity is doubled the photo current remains unchanged.
Reason. The photo electric current varies directly with the intensity of light and frequency of light.
(a) A
(b) B
(c) C
(d) D

Answer: d

Case Based Questions

The photoelectric emission is possible only if the incident light is in the form of packets of energy,
each having a definite value, more than the work function of the metal. This shows that light is not of wave nature but of particle nature. It is due to this reason that photoelectric emission was accounted by quantum theory of light.

Question. Packet of energy are called
(a) electron
(b) quanta
(c) frequency
(d) neutron

Answer: b

Question. One quantum of radiation is called
(a) meter
(b) meson
(c) photon
(d) quark

Answer: c

Question. Energy associated with each photon
(a) hc
(b) mc
(c) hv
(d) hk

Answer: c

Question. Which of the following waves can produce photo electric effect
(a) UV radiation
(b) Infrared radiation
(c) Radio waves
(d) Microwaves

Answer: a

Question. Work function of alkali metals is
(a) less than zero
(b) just equal to other metals
(c) greater than other metals
(d) quite less than other metals

Answer: d

According to de-Broglie a moving material particle sometimes acts as a wave and sometimes as a particle or a wave is associated with moving material particle which controls the particle in every respect. The wave associated with moving material particle is called matter wave or de-Broglie wave whose wavelength called de-Broglie wavelength, is given by λ = h/mv
Question. The dual nature of light is exhibited by
(a) diffraction and photo electric effect
(b) photoelectric effect
(c) refraction and interference
(d)diffraction and reflection.

Answer: a

Question. If the momentum of a particle is doubled , then its de-Broglie wavelength will
(a )remain unchanged
(b) become four times
(c) become two times
(d) become half

Answer: d

Question. If an electron and proton are propagating in the form of waves having the same λ , it implies that they have the same
(a)energy
(b)momentum
(c)velocity
(d)angular momentum

Answer: b

Question. Velocity of a body of mass m, having de-Broglie wavelength λ , is given by relation
(a) v = λ h/m
(b) v = λm/h
(c) v = λ/hm
(d) v = h/ λm

Answer: d

Question. Moving with the same velocity , which of the following has the longest de Broglie wavelength?
(a)ᵦ -particle
(b) α -particle
(c) proton
(d) neutron.

Answer: a