Question

A very long wire ABDMNDC is shown in figure carrying current I. AB and BC parts are straight, long and at right angle. At D wire forms a circular turn DMND of radius R. AB, BC parts are tangential to circular turn at N and D. Magnetic field at the centre of circle is :

Answer 1

Magnetic field of coil is directed outwards with respect to the page (right hand thumb rule).

Current in wire BC is along that in the coil hence magnetic field is in same direction (outwards).

Current in wire AB is against that in the coil hence magnetic field is in opposite direction (inwards).

|Bnet| = |(Bab - Bbc - Bdmnd)|

:-)