Question

How much charge is needed to repel another charge of 9.9 x 10^-6 N when they are 200m apart? Please help meee I really can't understand Coulomb's Law : (

Answer 1

The charge needed will be
`q=6.6\: \mu C`

Explanation:

The equation of the electric force is given by:

`F=k(qQ)/(r^(2))`

We have the force
`F = 9.9 10^(-6)\: N` and the distance r = 200. k is the Coulomb constant. Q and q are the charges.

We assume we have the same charge of the particles, so we have:

`q^(2)=(Fr^(2))/(k)`

`q^(2)=(9.9*10^(-6)200^(2))/(9*10^(9))`

`q=6.6*10^(-6)\: C`

Therefore, the charge needed will be
`q=6.6\: \mu C`

I hope it helps you!