A uniform straight wire XY of length 40 cm is fixed at both ends in a metre-bridge-like circuit. Upper resistance arms are 8 Ω and 12 Ω. To get zero galvanometer reading, free end J must be placed from B at: [Diagram: Image]
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Question

A uniform straight wire XY of length 40 cm is fixed at both ends in a metre-bridge-like circuit. Upper resistance arms are 8 Ω and 12 Ω. To get zero galvanometer reading, free end J must be placed from B at: [Diagram: Image]

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G1 Physics · Accepted Answer

Step 1: At balance, resistance ratio of upper arms equals ratio of wire lengths: 8/12 = XJ/JY. Step 2: XJ+JY=40 cm, so XJ=(8/20)×40=16 cm, JY=24 cm. Step 3: Source diagram labels B differently; if measured from the end marked B, crosscheck whether 16 cm or 24 cm is requested.