The force between two charged objects is 5.0 N. If one of the objects is replaced by an object with half the charge, what is the new force (assume distance is the same)?

The force between two charged objects is 5.0 N. If one of the objects is replaced by an object with half the charge, what is the new force (assume distance is the same)?

• A. 2.5 N
• B. 5.0 N
• C. 10 N
• D. 1.25 N

Answer: (A)

Coulomb’s law says the electrostatic force between two charges is proportional to the product of the charges and inversely proportional to the square of the distance between them. If the distance stays the same, the force scales with the product q1 q2. Halving one charge makes the product half as large, so the force becomes half of the original. Half of 5.0 N is 2.5 N. This matches the situation where one charge is reduced while everything else stays equal. If you changed both charges or the distance, the force would change in the corresponding way, but with just one charge halved at the same distance, you get 2.5 N.

Coulomb’s law says the electrostatic force between two charges is proportional to the product of the charges and inversely proportional to the square of the distance between them. If the distance stays the same, the force scales with the product q1 q2.

Halving one charge makes the product half as large, so the force becomes half of the original. Half of 5.0 N is 2.5 N. This matches the situation where one charge is reduced while everything else stays equal. If you changed both charges or the distance, the force would change in the corresponding way, but with just one charge halved at the same distance, you get 2.5 N.