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A potentiometer wire AB having length L and resistance 12 r is joined to a cell D of emf ε and internal resistance r. A cell C having emf ε /2 and internal resistance 3r is connected. The length AJ at which the galvanometer as shown in figure shows no deflection is – J C G A B + – 2 ε ,3r ε , r D + –

1. 12 11 L
2. 24 13 L
3. 12 5 L
4. 24 11 L

Correct answer: 24 13 L

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