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Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsDual Nature of Radiation and Matter3 Marks
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, $\text{V}_{0} = \frac{\phi_0}{\text{h}}$.

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