Question

find B at the point O due to the flow of electric current i in the wire having straight & semi-circular portion as shown :​

Answer 1

Magnetic field due to current in circular wire is largely axial. It means that we need to concentrate our investigation of magnetic field on axial positions. One of the important axial positions is center of the circular wire itself. We shall limit our discussion in this module to this case of magnetic field at the center of circular coil. The procedure for deriving expression for the magnetic field due to current in circular wire is same as that of current carrying straight wire. Here also, we make use of superposition principle whereby we combine the small magnetic fields due to each of the small current elements composing the circular coil.