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?

The magnetic field lines due to a current carrying circular loop can be shown with the help of following diagram:

Magnetic field lines are in the form of concentric circles in a circular current carrying conductor. Magnetic field lines are strong near the periphery because magnetic field lines remain close when they are near to the conductor

When we move towards the centre of the conductor, the magnetic field lines distant each other and at the centre, the arc appear of big circles.

On increasing the number of coils in the circular loop, the magnitude of the magnetic field increases and is equal to n times with n number of coils in the loop.