In a meter-bridge circuit, a known 100 Ω resistance is in the left arm and the unknown resistance R is in the right arm. The balance point is 40 cm from the left end. If a millimetre scale is used, determine R with its measurement uncertainty. Image
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Question

In a meter-bridge circuit, a known 100 Ω resistance is in the left arm and the unknown resistance R is in the right arm. The balance point is 40 cm from the left end. If a millimetre scale is used, determine R with its measurement uncertainty. Image

Options

G1 Physics · Accepted Answer

At balance, 100/R = 40/60, giving R = 150 Ω. The millimetre-scale uncertainty in balance length is propagated through R = 100(100−l)/l. Using Δl ≈1 mm gives the uncertainty represented by option C in the source. Correct answer: C.