00:01
Let's say we have two point charges, q prime and q.
00:05
And q prime, we're told, is four times as strong as the other.
00:09
And there's a certain distance apart in air.
00:11
Let's call this distance d.
00:12
And the force, we're told, is 0 .4 newtons.
00:16
And then the distance is decreased by 10 centimeters.
00:21
And then we're told the force is measured to be 0 .5 newtons.
00:25
So we want to calculate the charges and their original separation.
00:27
So what we'll have is f, of course, is going to be k, and then we can write this as q prime, which is 4q squared over d squared.
00:38
And then f prime should be 4kq squared over d minus 0 .1 meters squared...