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Reviewed CSCA Physics question · Standard

Light of frequency 1.0 x 10^15 Hz is incident on a metal with work function 3.0 eV. What is the maximum kinetic energy of the emitted photoelectrons? (Use h = 4.14 x 10^-15 eV·s)

  1. 1.14 eV
  2. 3.0 eV
  3. 4.14 eV
  4. 7.14 eV
Show the answer and explanation

Correct answer

A. 1.14 eV

Principle or equation

Einstein's photoelectric equation: K_max = h*f - work function.

Why this answer is correct

Photon energy E = h*f = (4.14e-15) * (1.0e15) = 4.14 eV. Then K_max = 4.14 - 3.0 = 1.14 eV.

Example

If h*f = 5 eV and work function = 2 eV, K_max = 3 eV.

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