Question

In a photoelectric experiment set-up, photons of energy 5 eV falls on the cathode having work function 3 eV. (a) If the saturation current is iA = 4pA for intensity 10 5 W /m2, then plot a graph between anode potential and current, (b) Also draw a graph for intensity of incident radiation $2\times 10^{-5}W/m2$

Answer 1

Maximum kinetic energy of the photoelectrons would be
$K_{max}=E-W=(5-3)eV=2eV$
Therefore, the stopping potential is 2 V. Saturation current depends on the intensity of light incident. When the intensity is doubled the saturation current will also become two fold.The corresponding graphs are shown in above figure.