If distance between two charges doubles, the force magnitude becomes

If distance between two charges doubles, the force magnitude becomes

• A. Twice as large
• B. Four times as large
• C. Half as large
• D. One quarter as large

Answer: (D)

The force between two point charges follows Coulomb’s law, which says it scales as the inverse square of the separation: F ∝ 1/r^2. If you double the distance (r becomes 2r), the force becomes F ∝ 1/(2r)^2 = 1/4 · (1/r^2). So the force drops to one quarter of its original magnitude. This is why increasing separation markedly reduces the interaction strength: the interaction is spread over a larger area, weakening the field by a factor of four.

The force between two point charges follows Coulomb’s law, which says it scales as the inverse square of the separation: F ∝ 1/r^2. If you double the distance (r becomes 2r), the force becomes F ∝ 1/(2r)^2 = 1/4 · (1/r^2). So the force drops to one quarter of its original magnitude. This is why increasing separation markedly reduces the interaction strength: the interaction is spread over a larger area, weakening the field by a factor of four.