Question

What is the electric potential energy of a charge that experiences a force of 3.6 × 10–4 N when it is 9.8 × 10–5 m from the source of the electric field?

3.5 × 10–8 J
4.6 × 10–4 J
2.7 × 10–1 J
3.7 × 100 J

Answer 1

Use U = F·r (since U = kq1q2/r and F = kq1q2/r^2 ⇒ U = Fr).

U = (3.6 × 10^−4 N)(9.8 × 10^−5 m) = 3.528 × 10^−8 J ≈ 3.5 × 10^−8 J.

Answer: 3.5 × 10^−8 J.