Question

The electrons are emitted in the photoelectric effect from a metal surface

• A.
  Only if the frequency of the incident radiation is above a certain threshold value
• B. Only if the temperature of the surface is high
• C. At a rate that is independent of the nature of the metal
• D. With a maximum velocity proportional to the frequency of the incident radiation

Answer 1

The correct option is A

Only if the frequency of the incident radiation is above a certain threshold value

The electrons are emitted in the photoelectric effect from a metal surface only if the light has enough energy, i.e. a minimum frequency is required, that we call as threshold frequency.