Q 12-08-048JEE MainJEE Main 2025 (29 Jan, Shift 1)Easy
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
**Assertion (A):** Electromagnetic waves carry energy but not momentum.
**Reason (R):** Mass of a photon is zero.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer: (C) (A) is false but (R) is true
**(A)** EM waves carry momentum as well as energy: a wave carrying energy $U$ carries momentum $U/c$, which is why light exerts radiation pressure. False.
**(R)** A photon has zero rest mass. True. (Its momentum $p = E/c = h/\lambda$ is non-zero despite this.)
Solution by Sreeraj P, M.Sc Physics