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JAMB Physics 1993 Question 50

Question 50

Modern Physics

The kinetic energy of a photoelectron liberated from a metallic surface depends on the

  1. A.intensity of the incident radiation
  2. B.time duration of the incident radiation
  3. C.temperature of the incident radiation
  4. D.frequency of the incident radiation.
Show the answer and explanation

Answer: D (frequency of the incident radiation.)

Explanation

Einstein's equation: ½mv2max = hf − W, so the kinetic energy depends on the frequency; intensity only changes the number of electrons.