Question

What determines the intensity of light in the photon picture of light?

Answer 1

The photon density, that is the no. of photons per unit volume at a given point determine the intensity of light in the photon picture of light.

Infact the photon density $n$ and intensity $i$ related to each other by the relationship

$n=\frac{i}{h}\times c\times n$

:where, h is the planks constant, c is the speed of light and ñ is the frequency of incident light.