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Charges +q and –q are placed at points A and B respectively which are a distance 2L apart, C is the midpoint between A and B. The work done in moving a charge +Q along the semicircle CRD is
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qQ 2πε0L -
qQ 6πε0L -
- qQ 6πε0L -
qQ 4πε0L
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Correct Option: C
Potential at C = VC = 0
Potential at D = VD
| = k |  |  | + | = - | ||||
| L | 3L | 3 | L |
Potential difference
| VD - VC = | = | | - | . | | ||||||
| 3 | L | 4πε0 | 3 | L |
⇒ Work done = Q (VD - VC)
| = - | × | = | |||||
| 3 | 4πε0 | L | 6πε0L |
