Why do we need to square the separation in Coulomb's experiment?

[shio]

Coulomb experiment torsion balance.

I know that electrical force is inversely to the square of the separation r ...My question is why we take r square? why we need square? And another question, why Q1Q2(multiplication of charges) is proportional to electrical force? (why we need to multiply them?) I know it sounds like silly question..but I really want to know (my teacher didn't tell me anything .he told me "just remember the formula" )

Thank you in advance! :D

 

[Vanadium 50]

The answer is because if we measure the force as a function of distance it is proportional to 1/r^2. Similarly if we measure the force as a function of charge it is proportional to q. Since we want the equations to match reality, that's what they look like.

 

[just dani ok]

Maybe you would like to read this article
https://en.m.wikipedia.org/wiki/Inverse-square_law