The magnitude of magnetic induction at mid-point O due to current arrangement as shown in figure will be: Image
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The magnitude of magnetic induction at mid-point O due to current arrangement as shown in figure will be: Image

G1 Physics · Accepted Answer

Only the vertical portions BC and ET contribute at O. The distance of O from each vertical wire is a/2. For a semi-infinite straight wire, B = μ₀I/(4πr), so each contribution is μ₀I/[4π(a/2)] = μ₀I/(2πa). Both fields are in the same direction. Therefore B = μ₀I/(πa).