1) A circular loop of radius n0.3 lies parallel to a much bigger circular loop of radius 20 cm. The centre of the smaller radius 20 cm. The centre of the smaller loop on the axis of the bigger loop. The distance between their centres is 15 cm. If a current of 2.0 A flows through the bigger loop, then the flux linked with smaller loop is A) 9.1×10−11Wb B) 6×10−11Wb C) 3.3×10−11Wb D) 6.6×10−11Wb Answer: Option AExplanation:magnetic field at the centre of smaller loop B=μ0iR222(R22+x2)3/2 Area of smaller loop S=πR21 ∴ Flux through smaller loop Φ = BS Substituting the values we get, ϕ=9.1×10−11Wb