Question

Assertion : The threshold frequency of photoelectric effect supports the particle nature of light.
Reason : If frequency of incident light is less than the threshold frequency, electrons are not emitted from metal surface.
A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer 1

Correct Answer - B
(b) : There is no emission of photoelectrons till the freaquency of incident light is less than a minimum frequency, however intense light it may be. In photoelectric effect, it is a single particle collision. Intensity is `hvxxN`, where hv is the individual energy of the photon and N is the total number of proton. In the wave theory, the intensity is proportional, not only ti `v^(2)` but also to the amplitude squared. For the same frequency, increase in intensity only increase the number of photons (in the quantum theory of Einstein).