A metal plate that emit photoelectrons under the influence of blue light, may not emit photoelectrons under the influence of red light. Explain

Explanation

For emission of electrons from a metal surface, frequency of the incident light should be higher than the threshold frequency of the metal. Frequency of blue light is greater than the frequency of red light. If the frequency of blue light os higher than threshold frequency for the metal, electrons will be emitted. But if the frequency of red light is less than the threshold frequency, red light will not be able to emit electron from that metal surfce.