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

A monochromatic light source with an intensity of 5 mW emits 8 10¹⁵ photons per second. This light ejects photoelectrons from a metal surface. The stopping potential for this arrangement is 2.0 V . Determine the work function of the metal.

Options

  1. A5.9 eV
  2. B1.9 eV
  3. C2.0 eV
  4. D3.9 eV

Correct answer

B. 1.9 eV

Step-by-step solution

The energy of a single photon is given by E = P n Substituting the given values: E = 5 10⁻³ 8 10¹⁵ = 6.25 10⁻¹⁹ J Converting the energy into electron-volts: E = 6.25 10⁻¹⁹ 1.6 10⁻¹⁹ eV 3.9 eV From Einstein's photoelectric equation: E = + K_ Since the stopping potential is V_s = 2.0 V , the maximum kinetic energy is K_ = 2.0 eV . = E - K_ = 3.9 eV - 2.0 eV = 1.9 eV

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