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Physics - Current Electricity Question with Solution | TestHub

PhysicsCurrent ElectricityMicroscopicHard2 minQB

PhysicsHardsingle choice

A material ' $B$ ' has twice the specific resistance of ' $A$ '. A circular wire made of ' $B$ ' has twice the diameter of a wire made of ' $A$ '. Then for the two wires to have the same resistance, the ratio $ℓ_{A} / ℓ_{B}$ of their respective lengths must be

Options:

Answer:

Solution:

$R_{1} = \frac{ρ _{A} ℓ _{A}}{π R _{A}^{2}} R_{2} = \frac{ρ _{B} ℓ _{B}}{π R _{B}^{2}}$ $\frac{ℓ _{A}}{ℓ _{B}} = \frac{ρ _{B} R _{A}^{2}}{ρ _{A} R _{B}^{2}} = \frac{2 ρ _{A} R _{A}^{2}}{ρ _{A} \cdot 4 R _{A}^{2}} \Rightarrow \frac{ℓ _{B}}{ℓ _{A}} = 2$

Stream:JEESubject:PhysicsTopic:Current ElectricitySubtopic:Microscopic

⏱ 2mℹ️ Source: QB

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