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Dual Nature of Radiation and Matter
Photoelectric Effect – Stopping Potential
3 questions from 3 papers, each with its answer.
- questions
- 3
- papers
- 3
- years asked, 2017–2026
- 1 of 10
- of Dual Nature of Radiation and Matter
- 3.66%
Appears in
Concepts tested
- Photoelectric effect - stopping potential
- stopping-potential-anode-negative
- threshold frequency from stopping potentials
All Questions
2022 1 question
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When two monochromatic lights of frequency, $\upsilon$ and $\upsilon/2$ are incident on a photoelectric metal, their stopping potential becomes $V_s/2$ and $V_s$ respectively. The threshold frequency for this metal is :Using Einstein's equation $eV = h\nu - h\nu_{th}$: $\frac{eV_s}{2} = h\nu - h\nu_{th}$ ...(1) $eV_s = \frac{h\nu}{2} - h\nu_{th}$ ...(2) Solving (1) and (2) gives a negative threshold frequency, which is not possible – the data given in the question is incorrect. This question was declared a bonus.
2022 Phase 2 1 question
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The light rays having photons of energy 4.2 eV are falling on a metal surface having a work function of 2.2 eV. The stopping potential of the surface is:By Einstein's equation $h\nu=\phi+eV_s$: $4.2\ eV=2.2\ eV+eV_s \Rightarrow eV_s=2$ eV, so $V_s=2$ V.
2016 Phase II 1 question
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Photons with energy 5 eV are incident on a cathode C in a photoelectric cell. The maximum energy of emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectrons will reach the anode A, if the stopping potential of A relative to C is:
Work function 3 eV; 6 eV photons need 3 V retarding potential.
$eV_s = \frac{1}{2}mv_{max}^2 = h\nu - \phi_0$
$2 = 5 - \phi_0 \Rightarrow \phi_0 = 3$ eV
In the second case: $eV_s = 6 - 3 = 3$ eV $\Rightarrow V_s = 3$ V
$\therefore V_{AC} = -3$ V