Applications of Biot-Savart’s Law

Biot Savart’s law gives the magnitude of the magnetic field.

Magnetic field at the centre of a circular coil carrying current

a circular coil of radius r is carrying current I. The direction of ∆B is normal to the plane of the coil. Since the field due to every element of the circular coil will be in the same direction, the resultant is obtained by adding all the contributions at the centre of the loop.

When an observer looking at the circular coil at its either end finds the current to be flowing in the clockwise sense, the face of the coil behaves like the south pole of the equivalent magnet, i.e., Bis directed inwards. On the other hand, if the current is seen to flow in the anticlockwise sense, the face of the coil behaves like the north pole of the equivalent magnet or the field is directed out of that end.