physics
posted by simin .
Two identical small spheres possessing charges q1 and q2 are separated by distance r. Which change would produce the greatest increase in the magnitude of the electrostatic force that one sphere exerts on the other?
1) doubling charge q1
2) doubling r
3) doubling r and charge q1
4) doubling r and charges q1 and q2
the answer is 1 but why?

The end goal is to incrase but if r is doubled, because it is a denominator, the answer would turn out to be small