Question

A physicist found that a force of 1.32 N was measured between two charged spheres. The distance between the spheres was 95 cm. Calculate the force between the two spheres when the distance was increased to 1.25 m?

Answer 1

The electric force (and the gravitational force too) is inversely proportional
to the square of the distance between the objects involved.

In this question, the distance is increased by a factor of  (1.25/0.95) .

So the electric force will change by the factor of  (0.95/1.25)² .

The new force is

           (1.32 N) · (0.95/1.25)²  =  0.762... newton   (rounded)