Two concentric circular coils A and B have radii 20 cm and 10 cm respectively lie in the same plane. The current in coil A is 0.5 A in anticlockwise direction. The current in coil B so that net field

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Two concentric circular coils A and B have radii 20 cm and 10 cm respectively lie in the same plane. The current in coil A is 0.5 A in anticlockwise direction. The current in coil B so that net field at the common centre is zero, is

TestHub · Accepted Answer

Magnetic field at the centre of a circular loop B = 2 R μ 0 ​ NI ​ Net Magneitc field B net ​ = 0 (given) ∴ ​ ⇒ B net ​ = 2 × ( 0.2 ) μ 0 ​ N 1 ​ × 0.5 ​ − 2 × ( 0 ⋅ 1 ) μ 0 ​ N 1 ​ × x ​ ⇒ 0.2 μ 0 ​ N 1 ​ x ​ = 0.4 μ 0 ​ N 1 ​ 0.5 ​ x = 0.4 0.5 × 0.2 ​ = 0.25 A in clockwise direction ​

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