(a)[2]
Describe what is meant by the photoelectric effect.
(b(i))[2]
Light with wavelength $420\,\text{nm}$ is incident on the surface of each metal. State what is meant by a photon.
(b(ii))[2]
Calculate the energy of one photon of the incident light.
(b(iii))[1]
State whether photoelectric emission will occur from each of the metals. sodium: zinc: