i) A metal emits electrons only when the incident (light) radiation has frequency greater than critical frequency (υ0) called threshold frequency. Threshold frequency different for different metals. ii) Photoelectric current is directly proportional to intensity of light and independent of frequency. iii) The velocity of photoelectron is directly proportional to the frequency of light. iv)For a given metal surface, stopping potential is directly proportional to the frequency and is not dependent on intensity light. v)The rate of emission of photoelectrons from the photocathode is independent of its Temperature. vi) The process is instantaneous