Question

What is the direction of the magnetic field at the centre of a current-carrying loop if the current is in the clockwise direction?

• A. Parallel to the circular face of the coil from left to right
• B. Perpendicular to radius of the coil and coming outward
• C. Parallel to the circular face of the coil from right to left
• D. Perpendicular to radius of the coil and going inward

Answer 1

The correct option is B

Perpendicular to radius of the coil and coming outward

A current-carrying coil behaves like a thin disc magnet whose one face is a north pole and the other face is a south pole. The polarity of the two faces of the current carrying coil can be determined by using the clock face rule given below:

According to clock face rule, look at one face of the coil through which the current is passing:

1. If the current around the face of the coil flows in the clockwise direction, then that face of the coil is the south pole.

2. If the current around the face of the coil flows in the anticlockwise direction, then that face of the coil is the north pole.

Here, the direction of current in the coil is clockwise, so this face of the coil will act like the south pole and the other face will act like the north pole. Since the direction of magnetic field is from south pole to north pole inside the coil, so, here, the direction of the magnetic field is perpendicular to the surface of the coil from outward to inward.