SAT Subject Physics Practice Question 547: Answer and Explanation
3. Two point charges are separated by a small distance. When the distance between the two particles is halved, which of the following descriptions is true?
A. The particles attract one another.
B. The particles repel one another.
C. The particles exert the same force on one another.
D. The particles exert twice as much force on one another.
E. The particles exert four times as much force on one another.
Correct Answer: E
The correct answer is (E). The force the particles exert on one another increases as the inverse of the square of the distance between the two particles.