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Concepts Of Physics MCQ Edition [Volume 2]PhysicsPhotoelectric Effect and Wave–Particle Duality

A metal has a work function of 2.5 10⁻¹⁹ J . When the metal is illuminated by a light beam of frequency 6.0 10¹⁴ Hz , what is the stopping potential?

Options

  1. A0.91 V
  2. B1.56 V
  3. C0.45 V
  4. D2.48 V

Correct answer

A. 0.91 V

Step-by-step solution

The energy of the incident photon is given by E = h . Taking Planck's constant h = 6.6 10⁻³⁴ J s : E = (6.6 10⁻³⁴ J s ) (6.0 10¹⁴ Hz ) = 3.96 10⁻¹⁹ J According to Einstein's photoelectric equation, the maximum kinetic energy of the emitted photoelectrons is: K_ max = E - K_ max = 3.96 10⁻¹⁹ J - 2.5 10⁻¹⁹ J = 1.46 10⁻¹⁹ J The stopping potential V₀ is related to the maximum kinetic energy by K_ max = eV₀ . V₀ = K_ max e = 1.46 10⁻¹⁹ J 1.6 10⁻¹⁹ C = 0.9125 V Rounding off, we get V₀ 0.91 V .

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