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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:

Asked in JEE Main 5th April 2nd Shift 2026 · Momentum delivered: absorbed or reflected

• (1) Both (A) and (R) are true and (R) is the correct explanation of (A)
• (2) Both (A) and (R) are true but (R) is not the correct explanation of (A)
• (3) (A) is true but (R) is false
• (4) (A) is false but (R) is true

Step-by-step solution

Why the other options are wrong

• (1) (R) is true but it is not the cause of (A); pressure comes from p = U/c, not from the absence of mass
• (3) (R) is not false — the photon's rest mass really is zero
• (4) (A) is not false — a beam does exert measurable radiation pressure

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