Two wires A and B of equal lengths are connected in left and right gap of a metre bridge, null point is obtained at 40 cm from left end. Diameters of the wires A and B are in the ratio 3 : 1 . The rat

Question

Two wires A and B of equal lengths are connected in left and right gap of a metre bridge, null point is obtained at 40 cm from left end. Diameters of the wires A and B are in the ratio 3 : 1 . The ratio of specific resistance of A to that of B is

TestHub · Accepted Answer

ℓ A ​ R B ​ R A ​ ​ ∴ ρ B ​ ρ A ​ ​ ​ = ℓ B ​ r B ​ r A ​ ​ = 1 3 ​ = 6 4 ​ = 3 2 ​ = A A ​ ρ A ​ ℓ B ​ ​ × ρ B ​ ℓ B ​ A B ​ ​ = ρ B ​ ρ A ​ ​ × ℓ B ​ ℓ A ​ ​ × r A 2 ​ r B 2 ​ ​ = 3 2 ​ × 9 = 1 6 ​ ​

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