Question

Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength 6800 . Calculate threshold frequency (V0) and work function (W0) of the metal.

Answer 1

Wavelength of the radiation, λ = 6800 = 6800 x 10-10 m

Work function of the metal, W0 = hv0 = hc/λ

= {6.626 x 10-34 Js x 3 x 108 ms-1}/{6800 x 10-10 m}

= 2.91 x 10-19 J

and threshold frequency, v0 = W0/h = {2.92 x 10-19 J}/{6.626 x 10-34 Js} = 4.41 x 1014 *-1

or, v0 = 4.41 x 1014 Hz