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Physics - Current Electricity Question with Solution | TestHub

PhysicsCurrent ElectricityMicroscopicHard2 minQB

PhysicsHardsingle choice

The length of a given cylindrical wire is increased by $100%$ . Due to the consequent decrease in diameter the change in the resistance of the wire will be

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Answer:

Solution:

$L_{1} = 2 l$ or $(π r^{2} l) = (π r_{2}^{2}) (2 l)$ $\Rightarrow r_{2} = \frac{r}{2}$ $;$ $R = ρ \frac{1}{π ^{2}}$ $R_{new} = (ρ) \frac{21}{( π ) ( r / 2 ) ^{2}} = \frac{( ρ ) 4 l}{( π ) r ^{2}} = 4 \times R$ $∴ Δ R = 4 R - R = 3 R$ $\frac{Δ R}{R} % = \frac{3 R}{R} \times 100 = 300%$

Stream:JEESubject:PhysicsTopic:Current ElectricitySubtopic:Microscopic

⏱ 2mℹ️ Source: QB

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