If we go on increasing the wavelength of light incident on a metal surface, what change in the number of electrons and the energy take place?

Explanation

If we increase the wavelength of incident light then the energy of incident photon `E=hc//lambda` will decrease. Due to it, the energy of photoelectron emitted decrease, but the number of electrons. emitted will not change. When the wavelength of the incident light becomes greater than the threshold wavelength (i.e. the energy of the incident photon becomes less than the work function of metal) then no photoelectron will be emitted.