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?
Ans.
The magnetic field pattern due to a circular coil is as shown in the figure below:
The concentric circles represent the magnetic field around the circular coil.
For every point on the circular loop, as we move away from the wire, the concentric circles around it becomes larger and larger. At the center of the loop, the field appears as a straight line.
The magnetic field produced by current-carrying circular wire at a given point is directly proportional to the current flowing through the wire and number of turns of the wire.
If a current carrying coil has n turns, the current in each circular turns has the same direction. So, the field due to each turn adds up and the field produced at any point is n times as large as that produced by a single turn.