The resistance per centimeter of a meter bridge wire is r , with X Ω resistance in left gap. Balancing length from left end is at 40 cm with 25 Ω resistance in right gap. Now the wire is replaced by another wire of 2 r resistance per centimeter. The new balancing length for same settings will be at

Question

The resistance per centimeter of a meter bridge wire is r , with X Ω resistance in left gap. Balancing length from left end is at 40 cm with 25 Ω resistance in right gap. Now the wire is replaced by another wire of 2 r resistance per centimeter. The new balancing length for same settings will be at, 20 cm, 10 cm, 80 cm, 40 cm

MARKS App · Accepted Answer

For first case: X r l 1 = 25 r l 2 ... (i) For second case: X 2 r l ' 1 = 25 2 r l ' 2 ... (ii) From (i) and (ii), we get l ' 1 l 1 = l ' 2 l 2 also total length is constant. Therefore, balance length doesn't change and l ' 1 = l 1 = 40 cm

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