As per the diagram a point charge +q is placed at the origin O. Work done in taking another point charge −Q from the point A [coordinates (0, a)] to another point B [coordinates (a, 0)] along the straight path AB is [figure]
- zero
- ( qQ4 0 1a2 ) 2a
- ( -qQ4 0 1a2 ) 2a
- ( qQ4 0 1a2 ) a 2
Answer
(1) zero
Solution
Both A (0, a) and B (a, 0) are at distance a from the charge +q at O.
VA = VB = 14 0 qa
W = (-Q)(VB - VA) = 0
As per NCERT, no work is done in moving a charge between two points of the same potential, whatever the path.
Answer: (1)