Question

Explain how frequency of incident light varies with stopping potential.

Answer 1

1. The effect of frequency of incident light on stopping potential can be studied by keeping the intensity of the incident light constant.

2. The electrode potential varies for different frequencies of the incident light.

3. As the frequency is increased the photoelectrons are emitted with greater kinetic energies so that the retarding potential needed to stop the photoelectrons is also greater.

Variation of photocurrent with collector electrode potential for different frequencies of the incident radiation

4. From the graph between frequency and stopping potential, the stopping potential varies linearly with the frequency of the incident light.

5. The stopping potential is zero when no electrons are emitted below a certain frequency called threshold frequency.

Variation of stopping potential with frequency of the incident radiation for two metals