Two equal charges repel one another with a force of 4.0$\times$ 10^-4 N when they are 10 cm apart. (Coulomb's constant is k=9.0$\times$ 10⁹ N^.m²/C².)If they are moved until the separation is 5 cm, the repulsive force will be A) 0.25$\times$ 10^-4 N. B) 1.0$\times$ 10^-4 N. C) 4.0$\times$ 10^-4 N. D) 16$\times$ 10^-4 N. E) 64$\times$ 10^-4 N.

Question

Quizplus · Accepted Answer

The force between two charges is inversely proportional to the square of the distance between them, so when the distance is halved (i.e. goes from 10 cm to 5 cm), the force will increase by a factor of 4 (2 squared). Therefore, the repulsive force will be 16 times greater, which is 16 N.

Two Equal Charges Repel One Another with a Force of 4.0