An infinitely long straight wire carrying current I is bent in a planer shape as shown in the diagram. The radius of the circular part is r. The magnetic field at the centre O of the circular loop is :

Question

G1 Physics · Accepted Answer

The magnetic field at O is the vector sum of the fields produced by the two straight semi-infinite parts and the circular part. Each straight semi-infinite segment is at perpendicular distance r from O. Its field magnitude is B(straight) = μ₀I/(4πr). The two straight segments produce fields in the same +î direction at O. Therefore their combined field is B⃗(straight,total) = [μ₀I/(2πr)] î. The circular part produces a field of magnitude B(circle) = μ₀I/(2r), directed along -î for the current di…