Question

Intensity of light is

• A. number of photons falling over an area is $1s$
• B. number of photons falling over an area
• C. number of photons falling over unit area in unit time
• D. number of photons emitted by source in $1s$

Answer 1

Answer: (C)

Intensity of light of a given frequency is determined by the number of energy quanta (photon) per unit area per unit time.