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In an experiment on photoelectric emission from a metallic surface, the wavelength of incident light is 2 × 10 - 7 m and stopping potential is 2 . 5 V . The threshold frequency of the metal (in Hz ) approximately is (charge on electron e = 1.6 × 10 - 19 C, Planck's constant h = 6.6 × 10 - 34 J s )

Options

  1. A12 × 10 15
  2. B9 × 10 15
  3. C9 × 10 14
  4. D12 × 10 13

Correct answer

C. 9 × 10 14

Step-by-step solution

e V 0 = h ν - h ν 0 ∴ Threshold frequency, ν 0 = v - e V 0 h = c λ - e V 0 h ∴           ν 0 = 3 × 10 8 2 × 10 - 7 - 1.6 × 10 - 19 × 2.5 6.6 × 10 - 34 =   9 .0 × 10 14   Hz

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