AP EAPCET 19-Aug-2021 Shift 1 Paper

Given, wavelength of radiation =300‌nm
=300×10−9m
Intensity I=100W∕m2
Number of photons falling on the surface,
np=

λ

hc

=

300×10−9

6.63×10−14×3×108

=0.1508×1019
As only 2% produce photoelectrons. So, number of photoelectrons ejected.
ne=

2

100

×0.1508×1019=0.302×1017
∴ Number of photoelectrons emitted from 2cm2 area =2×10−4×ne
=0.604×1013=6.04×1012