Question

Assertion : Photoelectric emission is an instantaneous process.
Reason : There is no time lag between incidence of light and emission of photoelectron.

• A. Both assertion and reason are true and reason is the correct explanation of assertion
• B. Both assertion and reason are true but reason is not the correct explanation of assertion
• C. Assertion is true but reason is faise
• D. Both assertion and reason are false

Answer 1

Answer: (A)

There is no time lag between the instant the photon of light falls on the metal surface and the instant a photoelectron is emitted from the metal surface. lt cannot be explained by assuming wave nature of radiation. If wave nature of radiation is assumed, then it will take quite a long time (about an year) for electron to come out of the metal surface.