First slide

Photo Electric Effect

Question

Light from a hydrogen discharge tube is incident on the cathode of a photoelectric cell the work function of the cathode surface is 4.2 eV. In order to reduce the photocurrent to zero the voltage of the anode relative to the cathode must be made

Moderate

A

- 4.2 V
B

- 9.4 V
C

-17.8 V
D

+9.4 V

Solution

$\begin{array}{l} E = W_{o} + {eV}_{o} \\ For hydrogen atom, E = + 13 .6 eV \\ ∴ + 13 .6 = 4 .2 + {eV}_{o} \Rightarrow V_{o} = \frac{(13 .6 - 4 .2) eV}{e} = 9 .4 V \\ Potential at anode = - 9 .4 V \end{array}$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App