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NEET2026PhysicsChapterActual

When a certain metallic surface is illuminated with monochromatic light of wavelength , the stopping potential for the photoelectric current is V₀ . When the exact same surface is illuminated with light of wavelength 2 , the stopping potential drops to V₀ 4 . What is the threshold wavelength ( ₀ ) for this metallic surface?

Options

  1. A3
  2. B4 3
  3. C4
  4. D2

Correct answer

A. 3

Step-by-step solution

Using Einstein's photoelectric equation, eV₀ = hc - hc ₀ For the first case: eV₀ = hc - hc ₀ For the second case: eV₀ 4 = hc 2 - hc ₀ Multiplying the second equation by 4 gives: eV₀ = 2hc - 4hc ₀ Equating the two expressions for eV₀ : hc - hc ₀ = 2hc - 4hc ₀ Rearranging the terms: 4hc ₀ - hc ₀ = 2hc - hc 3hc ₀ = hc ₀ = 3 Answer: 3

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