Moving Charges and Magnetism Problems - Numerical 03

Two concentric circular coils X and Y of radii 16cm and 10cm respectively lie in the same vertical plane containing the north-south direction. Coil X has 20 turns and carries a current of 16 A; coil Y has 25 turns and carries a current of 18A. The direction of current in X is anticlockwise and in Y is clockwise for an observer looking at the coil facing west. Give the magnitude and direction of the net magnetic field due to the coils at their centre.

Sub Topics

Suggested solution:

Suggested solution:

Let B_y be the magnetic field at the centre of the coil Y due to the current I_y flowing in it. If N_y be the number of turns and r_y the radius of the coil, then

For an observer looking at the coil Y facing west, the current is flowing in the clockwise direction. So, the direction of field B_y is towards west.

If B_x is the magnetic field at the centre of coil X, then

For an observer looking at the coil X facing west, the current is flowing in the anticlockwise direction. So, the direction of field B_x is towards east.

So, the resultant magnetic field

will be in the direction of the bigger of the two vectors. The magnitude of

i.e., B will be equal to the difference of the magnitude of