Inverse Square Law: What & How to Prove It

[eddybob123]

What is the inverse square law and how do you prove it?

 

[berkeman]

What is the inverse square law and how do you prove it?

That sounds interesting. What is it? Could you provide a web link or two to help us understand your question?

How do you think something like that could be "proved"? What is the formula for the area of a sphere maybe?

 

[Rap]

For forces like electric, magnetic, and gravitation, the inverse square law says that the force from a point source gets weaker the further you go from the source of the force. It falls off as 1/r^2 where r is the distance you are from the source. You prove it by measuring it. Other things obey the inverse square law too. If you have a light source, then the amount of light landing on a fixed area (like a piece of paper) facing the source will fall off as you move the area further away. It will fall off as 1/r^2. This is the geometric inverse square law. If you have a piece of paper at distance r, and you move it to 2r, you will have to make it 2 squared or four times larger in order for it to look the same size. This kind of inverse square law you can prove with geometry.

 

[eddybob123]

are you sure? because human measurements can't really prove it

 

[Rap]

are u sure? cause human measurements can't really prove it

Some forces do not obey the inverse square law, so for a general force, you can't prove it.

For the geometrical inverse square law, you can prove it, by geometry.

 

[Born2bwire]

are you sure? because human measurements can't really prove it

Course we can prove it empirically. We take two pith balls and give them each a net charge and then measure the Coulombic force as a function of distance. We will see that the force drops off as 1/r^2 with some proportional constant.