Question

Explain with the help of a labelled diagram the distribution of magnetic field due to a current through a circular loop. Why is it that if a current carrying coil has n turns the field produced at any point is n times as large as that produced by a single turn?

Answer 1

Electric current in a circular loop creates a magnetic field which is more concentrated in the center of the loop than outside the loop. Concentric circles are formed, which are centered at the point on both sides of the loop as shown in figure A. The lines near the center of the loop are almost straight. The magnetic field at the center of the loop is perpendicular to the plane of the loop. The concentric circles become larger as we move away from the wire because as the distance increases from the current carrying conductor the strength of the magnetic field fades away.
In same way, when we consider an electric current passing through a circular coil with n number of turns, say a solenoid, the strength of the magnetic field is directly proportional to the number of turns of the solenoid. That is, as the number of turns increases in the coil, the strength of the solenoid also increases. The diagrammatic representation is given above in figure B.