# MCQ Questions for Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter with Answers

Do you need help learning for your Class 12 Physics exam? Students may want to download NCERT MCQ Questions for Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter with Answers Pdf free download. This Dual Nature of Radiation and Matter Class 12 MCQs Questions with Answers can help understand the concepts score better in your Class 12 Physics Exam, so make sure you practice these! Check out chapter-wise MCQ Questions for Class 12 Physics with Answers.

## Dual Nature of Radiation and Matter Class 12 MCQs Questions with Answers

Solve this Dual Nature of Radiation and Matter Multiple Choice Questions of Class 12 Physics Chapter 11 MCQ, so as not to miss out on any concept from being clear about what they mean!

I. Choose the correct answer

Question 1.
When the light of frequency 2v0 (where v0 is threshold frequency) is incident on a metal plate, the maximum velocity of electrons emitted is v1. When the frequency of the incident radiation is increased to 5v0, the maximum velocity of electrons emitted from the same plate is v2. The ratio of v1 to v2 is:
(a) 1 : 2
(b) 1 : 4
(c) 4 : 1
(d) 2 : 1

Answer

Answer: (a) 1 : 2

Question 2.
The wavelength of a photon needed to remove a proton from a nucleus which is bound to the nucleus with 1 MeV energy is nearly
(a) 1.2 nm
(b) 1.2 × 10-3 nm
(c) 1.2 × 10-6 nm
(d) 1.2 × 101 nm

Answer

Answer: (b) 1.2 × 10-3 nm

Question 3.
A proton, a neutron, an electron and an a-particle have same energy. Then their de-Broglie wavelengths compare as
(a) λp = λn > λe > λa
(b) λα < λp = λn > λe
(c) λe < λp = λn > λa
(d) λe = λp = λn = λa

Answer

Answer: (b) λα < λp = λn > λe

Question 4.
The photoelectric threshold wavelength of silver is 3250 × 10-10 m. The velocity of the electron ejected from a silver surface by ultraviolet light of wavelength 2536 × 10-10 m is:
(Given h = 4.14 × 10-15 eVs and c = 3 × 108 m s-1)
(a) = 0.6 × 105 m s-1
(b) = 61 × 10³ m s-1
(c) = 0.3 × 106 m s-1
(d) = 6 × 105 m s-1

Answer

Answer: (d) = 6 × 105 m s-1

Question 5.
An electron beam is accelerated by a potential difference V to hit a metallic target to produce X-rays. It produces continuous as well as characteristic X-rays. If λmin is the smallest possible wavelength of X-ray in the spectrum, the variation of log λmin with log V is correctly represented in:

Answer

Answer:

Question 6.
Photons with energy 5 eV are incident on a cathode C in a photoelectric cell. The maximum energy of emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectrons will reach the anode A, if the stopping potential of A relative to C is
(a) – 1 V
(b) – 3 V
(b) + 3 V
(d) + 4 V

Answer

Answer: (b) – 3 V

Question 7.
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) H°
(d) H-1/2

Answer

Answer: (d) H-1/2

Question 8.
An electron is moving with an initial velocity $$\vec {v}$$ = v0$$\hat {j}$$ and is in a magnetic field
$$\vec {B}$$ = B0$$\hat {j}$$. Then its de-Broglie wavelength
(a) remains constant
(b) increases with time
(c) decreases with time
(d) increases and decreases periodically

Answer

Answer: (a) remains constant

Question 9.
An electron (mass m) with an initial velocity $$\vec {v}$$ = v0$$\hat {j}$$ is in an electric field
$$\vec {E}$$ = E0$$\hat {j}$$. If λ0 = $$\frac { h }{mv_0}$$, its de-Broglie wavelength at time t is given by
(a) λ0
(b) λ0 $$\sqrt{1+\left(\frac{e E_{0} t}{m v_{0}}\right)^{0}}$$
(c) $$\frac{\lambda_{0}}{\sqrt{1+\left(\frac{e E_{0} t^{t}}{m v_{0}}\right)^{2}}}$$
(d) $$\frac{\lambda_{0}}{1+\left(\frac{e E_{0} t}{m v_{0}}\right)^{2}}$$

Answer

Answer: (c) $$\frac{\lambda_{0}}{\sqrt{1+\left(\frac{e E_{0} t^{t}}{m v_{0}}\right)^{2}}}$$

II. Fill in the blanks

Question 1.
……………… is the phenomenon of the emission of electrons from a metal surface when radiation of suitable frequency falls on the metal surface.

Answer

Answer: Photoelectric effect

Question 2.
The phenomenon of emission of electrons from a hot metal surface is called ………………

Answer

Answer: Thermionic emission

Question 3.
The minimum energy required by a free electron to just escape from the metal surface is called ………………

Answer

Answer: Work function

Question 4.
This unit of energy commonly used in atomic and nuclear physics is ………………

Answer

Answer: Electron volt (eV)

Question 5.
The work function (Ø0) depends on the properties of the metal and the ……………… of its surface.

Answer

Answer: Nature

Question 6.
……………… is defined as the energy acquired by an electron when it is accelerated through a potential difference of 1 volt.

Answer

Answer: Electron volt

Question 7.
The energy of the photon is given by ………………

Answer

Answer: E = hv = $$\frac { hc }{λ}$$.

Question 8.
The velocity of photon in different media is ………………

Answer

Answer: Different

Question 9.
The rest mass of a photon is ………………

Answer

Answer: Zero

Question 10.
In a photon-particle collision (such as photon-electron collision), the total ……………… and total momentum are conserved.

Answer

Answer: Energy

Question 11.
The maximum kinetic energy of emitted photoelectrons depends on the ……………… of incident radiation and the nature of material.

Answer

Answer: Frequency

Question 12.
The maximum kinetic energy of emitted photoelectrons is independent of ……………… of incident radiation.

Answer

Answer: Intensity

Question 13.
The photoelectric current of emitted photoelectrons depends on the ……………… of incident radiation.

Answer

Answer: Intensity

Question 14.
The photo-electric current of emitted photoelectrons is independent of the ……………… of incident radiation.

Answer

Answer: Frequency

Question 15.
The minimum frequency required to eject an electron from the surface of a metal surface is called ……………… frequency.

Answer

Answer: Threshold

Question 16.
For a frequency v of incident radiation, ……………… than the cut-off frequency v0, no photoelectric emission is possible even if the intensity is large.

Answer

Answer: lower

Question 17.
Photons are electrically ……………… and are not deflected by electric and magnetic fields.

Answer

Answer: Neutral

Question 18.
Davison-Germer experiment verified the ……………… nature of moving electrons.

Answer

Answer: Wave

Question 19.
The expression for de-Broglie wavelength of an electron moving under a potential difference of V volt is ………………

Answer

Answer: λ = $$\frac { 1.227 }{√V}$$ nm

This NCERT MCQ Questions for Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter with Answers Pdf free download has been put together to help students understand the CBSE Class 12 Physics Dual Nature of Radiation and Matter MCQs Multiple Choice Questions with Answers. Hope you found this helpful!

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