Question 14: If c is the velocity of light in free space, the correct statements about photon among the following are:
A. The energy of a photon is E=h v
B. The velocity of a photon is c.
C. The momentum of a photon, \mathrm{p}=\frac{\mathrm{h} v}{\mathrm{c}}
D. In a photon-electron collision, both total energy and total momentum are conserved.
E. Photon possesses positive charge.
Choose the correct answer from the options given below:
(1) A and B only
(2) A, B, C and D only
(3) A, C and D only
(4) A, B, D and E only
Answer: Option (2)
Explanation:
A photon is a quantum of electromagnetic radiation and has well-defined energy, momentum, and speed in free space.
The energy of a photon is given by E=h v,
where h is Planck’s constant and v is the frequency,
so statement A is correct.
A photon always travels with the speed of light in free space,
which is c, therefore statement B is correct.
The momentum of a photon is related to its energy by p=\frac{E}{c}.
Substituting E=h v, we get p=\frac{h v}{c},
so statement C is correct.
In a photon-electron collision, such as Compton scattering,
both total energy and total momentum are conserved according to the laws of conservation,
hence statement D is correct.
A photon is electrically neutral and does not possess any charge,
so statement E is incorrect.
Therefore, the correct set of statements is A, B, C, and D.