Two wires A and B have the same length of 44 cm, and carry a current of 10 A each. Wire A is bent into a circle and wire B is bent into a square. (a) Which wire produces a greater magnetic field at the centre? (b) Obtain the magnitudes of the fields at the centres of the two wires.
The magnetic field at the centre of a circular coil is
Let us now consider the case of wire B which has been bent into a square as shown in the figure.
The magnetic field at C (centre of square PQRS) due to current carrying conductor PQ is given by
Magnetic field at the centre of the square is given by
B2 is clearly greater than B1.
