JEE Main · 2022 · 27 Jul 2022 · Shift 2 · Current Electricity

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In the given figure of meter bridge experiment, the balancing length AC corresponding to null deflection of the galvanometer is 40 cm. The balancing length, if the radius of the wire AB is doubled, will be ______ cm.

Answer: 40

Solution

In a meter bridge, the balancing condition is

\frac{R}{S} = \frac{l}{100 - l}

, where

l

is the balancing length. This ratio depends only on the resistances, not on the cross-sectional area of the bridge wire. When the radius of wire AB is doubled, its resistance changes, but the balancing length for a uniform wire remains independent of the wire's cross-sectional area. Therefore, the balancing length remains 40 cm.

JEE Main · 2022 · 27 Jul 2022 · Shift 2 · Integer answer

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