Light of energy 5eV falls on a metal of work function 3eV and electrons are…

Light of energy 5eV falls on a metal of work function 3eV and electrons are liberated. The stopping potential is
  • A.
    1.7V
  • B.
    2.0V
  • C.
    8.0V
  • D.
    15.0V
Correct Answer: Option B
Explanation

For a photoemitted electron,
eV = K.E.max, where V = stopping potential and K.E. = maximum kinetic energy of the photo emitted electron given by K.E. = Energy of incident rad – Work – function
= 5ev – 3ev = 2ev
∴ eV = 2eV
V = 2eV/e = 2V
∴ Stopping Potential = 2.0V

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