Question

An ultraviolet light beam having a wavelength of 130 nm is incident on a molybdenum surface with work finction of 4.4 eV. What is the stopping potential? (h = 6.63x10^-34 J * s, c = 3.00x10⁸ m/s, 1 eV = 1.6 x 10^-19 J, and 1nm = 10^-9 m).

Answer 1

Solution:

Stopping potential is the potential required to stop an electron, in Photoelectric effect.

Stopping potential depends on the kinetic energy and the frequency of the incident light.

e V = h c / -

where e = 1.6 x 10^-19 Coulombs is the charge on the electron ,

V = Stopping potential

V = [ (6.64 x 10^-34 ) ( 3 x 10^8) / ( 130 x 10^-9)  - ( 4.4 x 1.6 x 10^-19) ] / (1.6 x 10^-19)

= 5.18 volts