A current loop `ABCD` is held fixed on the plane of the paper as shown in figure. The arcs `BC( radius = b) and DA ( radius = a)` of the loop are joined by two straight wires `AB and CD` at the origin `O` is 30^(@)`. Another straight thin wire with steady current `I_(1)` flowing out of the plane of the paper is kept at the origin .

Due to the process of the current `I_(1)` at the origin:

A current loop ABCD is held fixed on the plane of the paper as shown in figure. The arcs BC( radius = b) and DA ( radius = a) of the loop are joined by two straight wires AB and CD at the origin O is 30^(@) . Another straight thin wire with steady current I_(1) flowing out of the plane of the paper is kept at the origin . The magnitude of the magnetic field (B) due to the loop ABCD at the origin (o) is :

A current loop ABCD is held fixed on the plane of the paper as shown in the figure. The arcs BC (radius = b) and DA radius = a) of the loop are joined by two straight wires AB and CD. A steady current I is flowing in the loop. Angle made by AB and CD at the origin O is 30^(@) . Another straight thin wire with steady current I_(1) flowing out of the plane of the paper is kept at the origin.

A current I flows in a long straight wire (into the plane of the paper) with cross-section having the from of a circular are of radius R a shown in the figure. Find the magnetic induction at the point O .

A current I flows in a long straight wire (into the plane of the paper) with cross-section having the from of a circular are of radius R a shown in the figure. Find the magnetic induction at the point O .