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In the photoelectric effect, when do electrons get ejected from a material?

1. at a rate proportional to the amplitude of the incoming radiation
2. with a maximum speed proportional to the frequency of the incident radiation
3. at a rate that does not depend on the emitter
4. only when the frequency of the incident radiation exceeds a definite threshold value

Correct answer: only when the frequency of the incident radiation exceeds a definite threshold value

Solution

Electrons are ejected from a material in the photoelectric effect only when the frequency of the incoming radiation is above a specific threshold, as this frequency provides the necessary energy to overcome the binding energy of the electrons in the material.

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