In the following diagram, the work done in moving a point charge from point P to point A, B and C are \( W_A, W_B, W_C \) respectively. Then (A, B, C are points on semicircle and point charge \( q \) is at the centre of semicircle)
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When a point charge moves along an equipotential surface, the work done is zero because the potential difference between the points remains the same.
In electrostatics, the work done in moving a point charge along any path depends only on the potential difference between the starting and ending points. Since the points A, B, and C are on the same equipotential surface (semicircle), the potential difference between them is the same. Therefore, the work done in moving the point charge from P to A, B, or C is equal and non-zero.
Thus, \( W_A = W_B = W_C \neq 0 \).