A point charge +q is placed at origin O. Work done in taking anothe...

Question

A point charge +q is placed at origin O. Work done in taking another point charge −Q from point A (0, a) to point B (a, 0) along straight path AB is

Accepted Answer

✅ Correct Answer: (A) Zero

📌 Concept: Conservative Nature of Electric Force

Step 1 — Distance from origin:
• Point A (0, a): r_A = √(0² + a²) = a
• Point B (a, 0): r_B = √(a² + 0²) = a

Step 2 — Potential at A and B:
V_A = k(+q)/a = kq/a
V_B = k(+q)/a = kq/a
∴ V_A = V_B

Step 3 — Work Done:
W = (−Q) × (V_B − V_A) = (−Q) × 0 = 0

∴ Work done = 0 (A and B lie on the same equipotential surface)

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