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MHT CET Medical202621 April 2026Evening ShiftPhysicsDual Nature of MatterActual

When light of wavelength ' ' is incident on a photosensitive surface, the stopping potential is ' V '. When light of wavelength ' 2 ' is incident on the same surface, the stopping potential is V/3 . Threshold wavelength for the surface is

Options

  1. A2
  2. B3
  3. C4
  4. D6

Correct answer

C. 4

Step-by-step solution

Using Einstein's photoelectric equation: eV = hc - eV 3 = hc 2 - Multiplying the second equation by 3 : eV = 3hc 2 - 3 Equating the two expressions for eV : hc - = 3hc 2 - 3 2 = 3hc 2 - hc 2 = hc 2 = hc 4 The work function is given by = hc ₀ , where ₀ is the threshold wavelength. hc ₀ = hc 4 ₀ = 4 Answer: 4

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