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Dual Nature of Radiation and Matter question

2022 · Q141
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Dual Nature of Radiation and Matter question

2022 · Q141

NEETPhysicsDual Nature of Radiation and MatterMCQ+4 / −1

When two monochromatic lights of frequency, v and v2{v \over 2}2v​ are incident on a photoelectric metal, their stopping potential becomes Vs2{{{V_s}} \over 2}2Vs​​ and Vs respectively. The threshold frequency for this metal is

  1. A
    2v
  2. B
    3v
  3. C
    23{2 \over 3}32​v
  4. D
    32{3 \over 2}23​v
View written solutionFree

Correct answer: D

Since $${k_{\max }} = e{V_s} = hv - \phi $$

$${{e{V_s}} \over 2} = hv - h{v_0}$$ ....... (i)

$$e{V_s} = {{hv} \over 2} - h{v_0}$$ ...... (ii)

$${1 \over 2}\left[ {{{hv} \over 2} - h{v_0}} \right] = hv - h{v_0}$$

$$ \Rightarrow h{v_0} - {{h{v_0}} \over 2} = hv - {{hv} \over 4}$$

$$ \Rightarrow {{h{v_0}} \over 2} = {{3hv} \over 4}$$

$${v_0} = {{3v} \over 2}$$

* Language of question is wrongly framed. The values of stopping potentials should be interchanged.

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