Question

Calculate the cut-off wavelength for aluminium, which has a work function of 4.08 eV. Will photoelectrons be emitted when radiation of wavelength 400 nm is incident on an aluminium surface?

Answer 1

Determine the cut-off wavelength:

$$\lambda_c=\frac{hc}{W}=304\text{ nm}.$$

400 nm is greater than the cut-off wavelength, therefore, the photons have less energy and the photoelectrons will not be emitted.