In an experiment on photoelectric effect light of wavelength `400 nm` is incident on a metal plate at rate of `5W.` The potential of the collector plate is made sufficiently positive with respect to emitter so that the current reaches the saturation value. Assuming that on the average one out of every `10^6` photons is able to eject a photoelectron, find the photocurrent in the circuit.

Options

A. `0.4mu A`
B. `0.8mu A`
C. `1.2mu A`
D. `1.6mu A`

Answer

D

Explanation

`P =n(hc)/(lambda)`
`n =(P lambda)/(hc) =(5xx400xx10^(-9))/(6.6xx10^(-34)xx3xx10^(8)) =10^(19)`
Number of electrons ejected / sec `=n' = (n)/(10^(6)) =(10^(19))/(10^(6)) =10^(13)`
Saturation current `i = n'e =10^(13)xx1.6xx10^(-19)`
`=1.6xx10^(-6) A= 1.6 mu A`