Find work function with stopping potential

Question

Ultraviolet laser at 248nm is incident on a surface and results in the photoemission from the surface.
(a)What is the work function of the surface? Assume the stoping potential is 2V.
(b)What is the maximum kinetic energyof the photoelectrons?

Answer 1

a. Work Function = eV_s  where V_s is the stopping potential.

b. Max. KE = hf - eV_s = hc/λ - eV_s

h = Planck's constant

λ = wavelength = 248 x 10^-9 m

V_s = 2 V

e = 1.6 x 10 ^-19 C

c = 3.0 x 10⁸ m/s