All the books and internet articles I have read so far claimed that the stopping potential and the maximum kinetic energy attained by a photoelectron is independent of the intensity with which the light emanates. But stopping potential is proportional to the frequency of light and,

$$I=\frac{nh\nu}{A}$$ where

  • $n$ = number of photons incident per unit time
  • $h$ = Planck's Constant
  • $\nu$ = the frequency of light
  • $A$ = area

How does this make sense?

  • 2
    $\begingroup$ so what are you expressing or expecting from that equation ? $\endgroup$
    – Ankit
    Dec 5, 2020 at 14:44

1 Answer 1


That is the whole point of photoelectric effect experiment, This experiment proves that particle nature of light exists, Here light acts particles, with energy packets, i.e have discrete energy, with energy equal to $E= h \nu$, $\nu$=frequency, Since this frequency dependent energy is given to free electrons in metal, they are ejected from surface, hence energy required to stop them is also frequency dependent and not intensity dependent.


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