Question

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:

• A. Both (A) and (R) are true and (R) is the correct explanation of (A)
• B. (A) is false but (R) is true
• C. Both (A) and (R) are true but (R) is not the correct explanation of (A)
• D. (A) is true but (R) is false

Hint:

Remember that the momentum of a photon is not directly related to its mass (since it has zero rest mass), but instead is given by the energy of the photon divided by the speed of light.

Answer 1

The Correct Option is C

- Assertion (A) is true: Electromagnetic waves do indeed carry energy and momentum. The momentum of electromagnetic waves is related to their energy by \( p = \frac{E}{c} \), where \( c \) is the speed of light, and \( E \) is the energy of the wave. 
- Reason (R) is also true: The mass of a photon is zero, but this does not imply that electromagnetic waves do not carry momentum. Photons carry momentum even though they have no rest mass. However, Reason (R) does not correctly explain Assertion (A), because the zero mass of photons does not prevent them from carrying momentum. Thus, the correct answer is (3).