Two positive point charges are a fixed distance apart. the sumof their charges is qt. what charge must each have inorder to (a) maximize the electric force between them, and (b)minimize it?

(A) both charge should be equal (b) one charge should be zero and is

Explanation:

We have given the sum of charges is

Let one charge is q then other charge will be

According to coulombs law the force between the charges is given by

As q is variable as it changes so differentiate with respect to q

For maximum electric force

So

So for maximum force both the charge should be equal

(b) The minimum force will be the zero force for this one charge should be zero and one is