Question

Assertion (A): Photoelectric effect is a spontaneous phenomenon.

Reason (R): According to the wave picture of radiation, an electron would take hours/days to absorb sufficient energy to overcome the work function and come out from a metal surface.

पर्याय

• Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

• Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

• Assertion (A) is true, but Reason (R) is false.

• Both Assertion (A) and Reason (R) are false.

Answer 1

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

Explanation:

Assertion (A) is true. The photoelectric effect is an instantaneous (spontaneous) process, occurring within roughly

Reason (R) is true. Classically, the wave theory predicted that energy would be distributed over the entire wavefront, meaning a single electron would need a long time (hours or days) to accumulate enough energy to escape.

Reason (R) is not the explanation. While (R) highlights a failure of the wave theory, it doesn’t explain why the effect is spontaneous. The actual explanation for the spontaneity is the particle (photon) nature of light, where a single photon transfers its entire energy to a single electron in a one-to-one collision.