In an aluminum (Al) bar of square cross section, a square hole is drilled and is filled with iron (Fe) as shown in the figure. The electrical resistivities of Al and Fe are $2.7 \times {10}^{- 8}Ωm$ and $1.0 \times {10}^{- 7}Ωm$ , respectively. The electrical resistance between the two faces P and Q of the composite bar is

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In an aluminum (Al) bar of square cross section, a square hole is drilled and is filled with iron (Fe) as shown in the figure. The electrical resistivities of Al and Fe are $2.7 \times {10}^{- 8}Ωm$ and $1.0 \times {10}^{- 7}Ωm$ , respectively. The electrical resistance between the two faces P and Q of the composite bar is

In an aluminum (Al) bar of square cross section, a square hole is drilled and is filled with iron (Fe) as shown in the

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Correct answer: B. (1875)/(64)μΩ

Aluminium A = ( 7 ^ 2 - 2 ^ 2 ) = 45m m ^ 2 ρ = 2.7 × 10 ^ - 8 Ωm l = 50mm R _ 1 = 2.7 × 10 ^ - 8 × 50 45 × 10 ^ - 3 Ω R _ 1 = 30μΩ R _ net = R _ 1 R _ 2 R _ 1 + R _ 2 = (30 × 1250)/(1280) = (3 × 125 × 5)/(64) R _ net = (1875)/(64)μΩ Ferrous A = 4m m ^ 2 ρ = 10 ^ - 7 Ωm l = 50mm R _ 2 = 10 ^ - 7 × 50 4 × 10 ^ - 3 Ω R _ 2 = 1250μΩ

In an aluminum (Al) bar of square cross section, a square hole is...

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