Question

Assertion : The kinetic energy of the emitted photoelectrons changes only with a change in the frequency of the incident radiations.
Reason : The kinetic energy of photo-electrons emitted by a photo-sensitive surface depends upon the intensity of the incident radiation.

• A. If both A and R are true, and R is a correct explanation of the A
• B. If both A and R are true, but R is not a correct explanation of the A
• C. If A is true, but R is false
• D. If both A and R are false

Answer 1

Answer: (C)

Einstein's photoelectric equation states that
$hv=h{v}_0+K{E}_{max}$
$\Rightarrow K{E}_{\max }=hv-h{v}_0=hv-W$
Where $W=h{v}_0=$ work function of the material
Therefore we see that the maximum kinetic energy of the emitted photoelctrons depends directly on the frequency of the incident radiations. It does not depend upon the intensity of the light used.