The separation between two point charges is doubled while the charges themselves stay the same. What happens to the electrostatic force between them?
AIt falls to a half
BIt doubles in size
CIt falls to a quarter
DIt stays the same
Answer & Solution
Correct answer: C. It falls to a quarter
1. The electrostatic force is inversely proportional to the square of the distance between the charges.
2. Doubling the distance means the square of the distance becomes four times as large.
3. Dividing by four times as much makes the force one quarter of its old value.
4. Halving the force would be the answer if the law were a simple inverse law rather than an inverse square law, which is the trap here.
_Source: Siyavula Physical Sciences Grade 11 (Everything Science, CC BY 4.0), Chapter 9: Electrostatics_
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