Question

The work function of a metal 3 eV. The colour of the visible light that is required to cause emission of photo electrons is :-

(1) Violet

(2) Red

(3) Yellow

(4) Green

Answer 1

Correct option is : (1) Violet

\(\phi_0 = E = \frac{hc}{\lambda} = \frac{1240}{\lambda}\)

\(\lambda = \frac{1240}{3} = 413.3\ nm\)