My question is that Power, which is energy per unit time P=Nhν/t as the formula suggests, can be increased in two ways, increasing no. of incident photons or increasing frequency.

If we increase no. of incident photons(keeping freq. constant) it automatically implies that stopping potential should not change.

But if we do increase in freq., Kinetic energy of electrons and hence stopping potential should increase, but it is a fact that increasing power doesn't change s.p. Why do we say so?


1 Answer 1


"increasing power doesn't change s.p.". This statement is misleading. It should read "increasing the power of the same wavelength of monochromatic light doesn't change the stopping potential. The standard explanation is that by increasing the power in this way, we are not changing the energies of the individual photons, but simply increasing the number of photons per second.


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