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]
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.