Question
Define the terms ‘stopping potential’ and ‘threshold frequency’ in relation to photoelectric effect. How does one determine these physical quantities using Einstein’s equation?
✓
Answer
Stopping Potential: The minimum negative potential applied to the anode/plate for which photoelectric current become zero.
Threshold frequency: The minimum (cut-off) frequency of incident radiation, below which no emission of photoelectrons takes place.
By Einstein‟s Equation $\text{𝑒𝑉}_{0} =\text{hv}− \phi_{o}$
For any given frequency $\text{𝑣} > \text{v}_{0} , \text{v}_{0}$ can be determined.
Stopping Potential $\text{𝑉}_{0} =\bigg(\frac{\text{h}}{\text{e}}\bigg)\text{v}−\frac{\phi_{o}}{e}$
as $\phi_{0} = \text{hv}_{0}$
Threshold frequency, $\text{V}_{0} = \frac{\phi_0}{\text{h}}$.
Threshold frequency: The minimum (cut-off) frequency of incident radiation, below which no emission of photoelectrons takes place.
By Einstein‟s Equation $\text{𝑒𝑉}_{0} =\text{hv}− \phi_{o}$
For any given frequency $\text{𝑣} > \text{v}_{0} , \text{v}_{0}$ can be determined.
Stopping Potential $\text{𝑉}_{0} =\bigg(\frac{\text{h}}{\text{e}}\bigg)\text{v}−\frac{\phi_{o}}{e}$
as $\phi_{0} = \text{hv}_{0}$
Threshold frequency, $\text{V}_{0} = \frac{\phi_0}{\text{h}}$.
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