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)