Question

The threshold energy for photoelectric emission of electrons from a metal is `3.056 xx 10^(-15)` joule. If light of `4000 Å` wavelength is used, will the electrons be efected or not ? (`h = 6.63 xx 10^(-34)` Joule sec)

Answer 1

Correct Answer - No
Electrons will be ejected only if the energy of incident light is greater than the threshold energy.
Energy of the incident light `= hv = h (c)/(lamda) = (6.63 xx 10^(-34) xx 3 xx 10^(8))/(4000 xx 10^(-10)) J = 4.97 xx 10^(-19) J`
Thus is less than threshold energy