Question

The photoelectric current in a photoelectric cell can be reduced to zero by a stopping potential of 1.8 volt. Monochromatic light of wavelength 2200Å is incident on the cathode. Find the maximum kinetic energy of the photoelectrons in joules. [Charge on electron = 1.6 x 10^-19 C]

Answer 1

Given:- V₀ = 1.8 V, e = 1.6 x 10^-19 C, λ = 2200 Å

To find:- Maximim kinetic energy (K.E.)_max

Formula:- (K.E.)_max = eV₀

Calculation: Using formula,

(K.E.)_max = 1.6 x 10^-19 x 1.8

∴ (K.E)max = 2.88 x 10^-19 J

Maximum kinetic energy of emitted photoelectron is 2.88 x 10^-19 J.