Given below are two statements: one is labelled as Assertion (A): and the other is labelled as Reason (R).
Assertion (A): The electromagnetic wave exerts pressure on the surface on which they are allowed to fall.
Reason (R): There is no mass associated with the electromagnetic waves.
In the light of the above statements, choose the correct answer from the options given below:
Assertion (A): The electromagnetic wave exerts pressure on the surface on which they are allowed to fall.
Reason (R): There is no mass associated with the electromagnetic waves.
In the light of the above statements, choose the correct answer from the options given below:
- (A)Both (A) and (R) are true and (R) is the correct explanation of (A)
- (B)Both (A) and (R) are true but (R) is not the correct explanation of (A)✓ Correct
- (C)(A) is true but (R) is false
- (D)(A) is false but (R) is true
Answer: (B)
Solution
Electromagnetic waves carry both energy and linear momentum, the momentum of a beam of energy being . When the wave strikes a surface this momentum is delivered to the surface, and the rate of momentum transfer is a force, producing a radiation pressure; so the assertion is true. Electromagnetic waves also possess no rest mass, so the reason is a true statement in its own right. However, the pressure originates from the momentum the wave carries, not from the absence of mass, so the two facts are independent and the reason does not explain the assertion. Both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.
JEE Main · 2026 · 05 Apr 2026 · Shift 2 · Single correct option