Question

Calculate the maximum kinetic energy of photoelectrons emitted by a metal (work function = 1.5 eV) when it is illuminated with light of wavelength 198 nm.

Answer 1

According to Einstein's photoelectric equation,

`"E"_k = hv - w = (hc)/lambda - w`

Here h = 6.6 × 10^-34 Js

c = 3.0 × 10⁸ ms^-1

λ = 198 × 10^-9 m

w = 1.5 × 1.6 × 10^-19 J 

`therefore "E"_k = ((6.6 xx 10^-34 xx 3.0 xx 10^8)/(198 xx 10^-9) - 1.5 xx 1.6 xx 10^-19)`J

= (10 × 10^-19 - 2.4 × 10^-19) J

= 7.6 × 10^-19 J