The inverse-square law generally applies when some force, energy, or other conserved quantity is evenly radiated outward from a point source in three-dimensional space. This means that if the intensity and the power/energy is known you can calculate the distance from the source.

The mathematical formula describes the relation between the intensity, the “power” and the distance from the source: I=P/4*Pi*r^2 (The I being the intensity in W/m² and P being power in Watts)

This means that every time you increase the distance (the radius in the circle) with n the same amount of energy has to be spread across an area that is n^2 times bigger.

Although our illustration is two-dimensional, the circles represent the three-dimensional spheres that are created with equal radii.

Here we use I = Power/(4*Pi*r²)
Please use SI-units (W/m² - W - m). Exponents of 10 like 1.5*10¹¹ is written: 1.5e+11

Intensity:  Power:  Distance: 

Insert one or more variables