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When a piece of metal is illuminated by monochromatic light of wavelength λ , then stopping potential is 3 V s . When the same surface is illuminated by the light of wavelength 2 λ , then stopping potential becomes V s . The value of threshold wavelength for photoelectric emission will be

Options

  1. A4 λ
  2. B8 λ
  3. C4 3 λ
  4. D6 λ

Correct answer

A. 4 λ

Step-by-step solution

According to Einstein's photoelectric equation e V = h c 1 λ - 1 λ 0 Ist case 3 e V s = h c 1 λ - 1 λ 0 ...(i) IInd case e V s = h c [ 1 2 λ - 1 λ 0 ] ...(ii) Dividing Eq. (i)by Eq. (ii), we get λ 0 = 4 λ

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