Intensity Formula

The intensity of a wave measures the power passing through a surface unit perpendicular to the direction of propagation of the wave.

Intensity = power/ surface perpendicular to the direction of propagation

The equation is written

I = P/S

We have:

I = Intensity

P = power

S = surface perpendicular to the direction of propagation

Intensity Questions:

1) Calculate the intensity of a wave whose power is 36kW and the area of cross section is 45km².

Answer: First calculate the intensity using the formula above, where P = 36kW and S = 45km²

I = P/S

I = 36*10³W/45*10⁶m²

I = 0,8*10³W/m².

2) Calculate the power of a wave whose intensity is 40x10^-4 W/m ² and cross section area is 800m².

Answer: First calculate the power by clearing P of the formula above, where I = 40x10^-4 W/m²and S = 800m²

I = P/S

P = I*S

P = 40x10^-4 W/m²* 800m²

P = 3.2W.