Statement-1: When ultraviolet light is incident on a photocell, its stopping potential is V0 and the maximum kinetic energy of the photoelectrons is Kmax. When the ultraviolet light is replaced by Xrays, both V0 and Kmax increase. Statement-2: Photoelectrons are emitted with speeds ranging from zero to a maximum value because of the range of frequencies present in the incident light.

Question

Statement-1: When ultraviolet light is incident on a photocell, its stopping potential is V0 and the maximum kinetic energy of the photoelectrons is Kmax. When the ultraviolet light is replaced by Xrays, both V0 and Kmax increase. Statement-2: Photoelectrons are emitted with speeds ranging from zero to a maximum value because of the range of frequencies present in the incident light. (A) Statement-1 is true, Statement-2 is true; Statement-2 is the correct explanation of Statement-1 (B) Statement-1 is true, Statement-2 is true; Statement-2 is not the correct explanation of Statement- 1 (C) Statement-1 is false, Statement-2 is true (D) Statement-1 is true, Statement-2 is false

Tardigrade Admin · Accepted Answer

Since the frequency of ultraviolet light is less than the frequency of X-rays, the energy of each incident photon will be more for X-rays

K . E_{p h o t oe l ec t ro n} = hn - φ

Stopping potential is to stop the fastest photoelectron

V_{0} = \frac{h v}{e} - \frac{φ}{e}

so,

K . E_{ma x}

and

V_{0}

both increases.
But K.E ranges from zero to

K . E_{ma x}

because of loss of energy due to subsequent collisions before getting ejected and not due to range of frequencies in the incident light.