Particle nature of light | Learn Physics

10 Question-answer on particle nature of light

1.       Planck’s constant has the dimensions of

(a)    Energy

(b)   Mass

(c)    Frequency

(d)   Angular momentum

Ans: ( d)

2.       A photon of frequency v has a momentum associated with it. If c is the velocity of light, this momentum is:

(a)    Hv/c²

(b)   Hvc

(c)    v/c

(d)   hv/c

Ans: (d)

3.       the energy of the visible light is of the order of

(a)    few eV

(b)   few MeV

(c)    Few keV

(d)   1/1000eV

Ans: (a)

4.       A metal surface is illuminated by the photons of energy 5eV and 2.5 eV respectively. The ratio of their wavelengths is:

(a)    1:3

(b)   1:4

(c)    2:1

(d)   1:2

Ans: (d)

5.       A photon will have less energy, if its

(a)    Amplitude is higher

(b)   Frequency is higher

(c)    Wavelength is longer

(d)   Wavelength is shorter

Ans: (c)

6.       It is essential to consider light as a stream of photons to explain

(a)    Diffraction of light

(b)   Refraction of light

(c)    Photoelectric effect

(d)   Reflection of light.

Ans: ( c)

7.       The energy of photon cannot be represented by

(a)    1240/λ

(b)   Hc/λ

(c)    Hcλ

(d)   Hv

Ans: (c)

8.       The number of photons required to give a definite energy varies

(a)    Inversely as the wavelength

(b)   Inversely as the frequency

(c)    Directly as the frequency

(d)   Independent of the frequency.

Ans: (b)

9.       Which of the following statement about photon is incorrect?

(a)    Photons exert no pressure

(b)   Momentum of photon is hv/c

(c)    Photon’s rest mass is zero

(d)   Photon’s energy is hv.

Ans: ( a)

10.       Which one of the following statement about photon is not correct?

(a)    Photons exert no pressure

(b)   Photons energy is hv

(c)    Momentum of photon is hv/c

(d)   Photons rest mass is zero.

Ans: (a)