Define the terms threshold frequency and stopping potential in relation to the phenomenon of photoelectric effect. How is the photoelectric current affected on increasing the (i) frequency (ii) intensity of the incident radiations and why?
Threshold frequency : The minimum frequency of incident radiation, which can eject electrons from a metal, is called threshold frequency. Below threshold frequency, there is no photoelectric emission.
Stopping potential : The minimum negative potential given to the anode of a photocell for which the photoelectric current becomes zero is called stopping potential.
(i) The increase of frequency of incident radiation has no effect on the photoelectric current.
(ii) The photoelectric current increases proportionally with the increase in intensity of incident radiation.