Two small,charged objects,Q1 and Q2,are some distance d apart from each other and there is a force F between them.What is the value of the force if Q1 is increased by a factor of two,Q2 is increased by a factor of 3,and d is increased by a factor of 5?
A)0.20 F
B)0.24 F
C)0.12 F
D)1.2 F

Question

Quizplus · Accepted Answer

The force between two charged objects is given by Coulomb's Law:
F = k(Q1Q2/d^2)
where k is a constant, Q1 and Q2 are the charges, and d is the distance between them. 
Since Q1 is increased by a factor of 2, Q1 becomes 2Q1. Similarly, Q2 becomes 3Q2 and d becomes 5d. Substituting these values in the equation, we get:
F' = k(2Q1)(3Q2)/(5d)^2 
F' = (6/25)k(Q1Q2/d^2) = (6/25)F
Therefore, the force becomes 0.24 F. The answer is B.

Two Small,charged Objects,Q1 and Q2,are Some Distance D Apart from Each