CBSE Class 12 · 2011 · All India · Current ElectricityShort Answer

In a metre-bridge experiment the balance point was observed at J with

A J = ℓ

.
(i) If the values of R and X are doubled and then interchanged, what is the new balance point?
(ii) If the galvanometer and the battery are interchanged at the balance position, how is the balance point affected?

Solution

At balance

\frac{R}{X} = \frac{ℓ}{100 - ℓ}

. (i) Doubling both keeps the ratio the same, but interchanging R and X inverts it, so the balancing length becomes

100 - ℓ

. (ii) The balance condition

\frac{R}{X} = \frac{ℓ}{100 - ℓ}

does not involve the galvanometer or cell positions, so swapping them leaves the balance point unchanged.

CBSE Class 12 Board · 2011 · All India · Subjective

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