The unit for measuring intensity is watt per m2.
What is Intensity?
The quantity of energy carried by a wave per unit time over a unit area surface is known as intensity, and it is proportional to the energy density multiplied by the wave speed. Watts per square metre is the most common unit of measurement. The strength and amplitude of a wave will determine its intensity. The letter I stands for intensity. The intensity formula is,
I = Intensity
P = Power
A = Area of cross-section