Question

photoelectric effect was first observed by hertz. the number of photoelectric effect is propotional to ------of the light used​

Answer 1

$\boxed{ \bf \red {Maximum \: K.E.}}$ of the released electrons did not vary with the intensity of the light, as expected according to the wave theory, but was proportional instead to the frequency of the light.

So correct Answer is $\boxed{ \bf \red {Maximum \: K.E.}}$