force variation with distance

Question

If distance between two point charges doubles, electrostatic force becomes?

RankGuru · Accepted Answer

1. **Force Relation**: From Coulomb's Law, $F = k \frac{q_1 q_2}{r^2}$. Thus, $F \propto 1/r^2$ (Inverse Square Law).
2. **Change Analysis**: Let the new distance be $r' = 2r$.
3. **Calculation**: $F_{new} = k \frac{q_1 q_2}{(2r)^2} = k \frac{q_1 q_2}{4 r^2} = \frac{1}{4} F$.
4. **Conclusion**: Doubling the distance reduces the force to **one-fourth** (a quarter) of its original value.

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force variation with distance

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