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PhysicsCurrent ElectricityEquivalent ResistanceEasy2 minPYQ_2024

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A conducting wire is stretched by applying a deforming force, so that its diameter decreases to $40%$ of original value. The percentage change in its resistance will be

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Answer:

Solution:

On stretching, volume of wire remains constant. So, $V = A l$ or $l = \frac{V}{A}$ $∴ ∴ R = ρ \cdot \frac{l}{A} = \frac{ρ V}{A ^{2}} = \frac{ρ V}{\frac{π ^{2} D ^{4}}{16}} = \frac{16 ρ V}{π ^{2} D ^{4}} \frac{Δ R}{R} = - 4 \frac{Δ D}{D} = - 4 (- 0.4) = 1.6%$

Stream:BITSATSubject:PhysicsTopic:Current ElectricitySubtopic:Equivalent Resistance

⏱ 2mℹ️ Source: PYQ_2024

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