Assertion : The threshold frequency of photoelectric effect supports the particle nature of sunlight .
Reason : If frequency of incident light is less than the threshold frequency , electrons are not emitted from metal surface.

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If the assertion and reason both are false.

Answer

B

Explanation

There is no emission of photoelectrons till the frequency 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 `hv xxN` where hv is the individual energy of the photon and N is the total number of photons. In the wave theory, the intensity is proportional, not only to `v^2` but also to the amplitude squared. For the same frequency, increase in intensity only increases the number of photons (in the quantum theory of Einstein).