Question

The photoelectric work function for a metal surface is 4.125ev. The cut-off wavelength for this surface is

Answer 1

given W = 4.125 e V = 4.125 * 1.6 * 10^-19 J

W = h c / λo

So required λo = h c / W = 6.626 * 10^-34 * 3 * 10^8 / (4.125 * 1.6 * 10^-19)

Simplifying you get λo = 3.011 * 10^-7 m