The resistance of a wire is R . It is bent at the middle by 18 0 ∘ and both the ends are twisted together to make a shorter wire. The resistance of the new wire is

Resistance of wire ( R ) = ρ A l If wire is bent in the middle then l ′ = 2 l , A ′ = 2 A ∴ New resistance, R ′ = ρ A ′ l ′ = 2 A ρ 2 l = 4 A ρl = 4 R .

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PhysicsCurrent ElectricityMicroscopicEasy2 minQB

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The resistance of a wire is $R$ . It is bent at the middle by $18 0^{\circ}$ and both the ends are twisted together to make a shorter wire. The resistance of the new wire is

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Resistance of wire $(R) = ρ \frac{l}{A}$ If wire is bent in the middle then
$l^{'} = \frac{l}{2}, A^{'} = 2 A ∴ New resistance, R^{'} = ρ \frac{l ^{'}}{A ^{'}} = \frac{ρ \frac{l}{2}}{2 A} = \frac{ρl}{4 A} = \frac{R}{4} .$

Stream:JEESubject:PhysicsTopic:Current ElectricitySubtopic:Microscopic

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