Question

Which of the following option(s) is/are correct for photons?

• A. Its rest mass is zero, but its energy is non-zero
• B. It carries non-zero linear momentum
• C. It carries zero spin angular momentum
• D. It has two linearly independent states of polarization

Hint:

Photons are massless particles with zero rest mass, but they carry energy, linear momentum, and spin angular momentum, and have two independent polarization states.

Answer 1

The Correct Option is A, B, D

1. Rest mass is zero, but energy is non-zero:
A photon is a massless particle, which means it has zero rest mass (\( m = 0 \)). However, it does carry energy, which is given by \( E = h \nu \), where \( \nu \) is the frequency of the photon and \( h \) is Planck's constant.
Therefore, (A) is correct.

2. Photon carries non-zero linear momentum:
A photon, despite having no rest mass, does carry linear momentum. The momentum of a photon is given by \( p = \frac{E}{c} = \frac{h \nu}{c} \), where \( c \) is the speed of light.
Therefore, (B) is correct.

3. Photon carries zero spin angular momentum:
Photons are spin-1 particles, meaning they do not have zero spin angular momentum. The spin of a photon can take two values, \( +1 \) or \( -1 \), corresponding to the two polarization states.
Therefore, (C) is incorrect.

4. Photon has two linearly independent states of polarization:
A photon, being a spin-1 particle, has two possible polarization states (right-handed and left-handed polarization). These are the two independent polarization states that photons can have.
Therefore, (D) is correct.