If the distance between two charges is halved and magnitude of charges are also doubled, then the force between these charges becomes:
- A. Two times
- B. Four times
- C. Eight times
- D. Sixteen times
Explanation
Doubling both charges multiplies the numerator of Coulomb's law by four, and halving the separation divides the denominator by four since the distance is squared, so the two effects combine to give sixteen times the original force. Handling the two changes separately and then multiplying is the safe method. Forgetting that the distance is squared gives the eight times answer.
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