A wire is bent in the form of a circular arc with a straight portion AB. Magnetic induction at O when current I is flowing in the wire, is
μ02r π−θ + tanθ
μ02πr π+θ − tanθ
μ0I2πr π−θ + tanθ
μ0I2πr −tanθ+π−θ
BAB = μ0I4πOC 2 sin θBut OC=r cos θor BAB = μ0I2πr tan θ
Magnetic field due to circular portion,
BAB' = μ0I2r2π−2θi2π = μ0I2πr π−θ
Total magnetic field
=μ0I2πr tan θ + μ0I2πrπ−θ=μ0I2πr tan θ + π−θ