Question

A neutral point is obtained at the centre of a vertical circular coil carrying current. The angle between the plane of the coil and the magnetic meridian is

• A. $0$
• B. ${45}^o$
• C. ${60}^o$
• D. ${90}^o$

Answer 1

The correct option is D ${90}^o$

Magnetic meridian is a vertical $N-S$ plane, the earth's magnetic field $\left(B_H\right)$ lies in it. ( For more details see magnetism).
To obtain neutral point at the centre of coil, magnetic field due to current $\left(B\right)$ and $B_H$ must cancel each other. Hence plane of the coil and magnetic meridian must be perpendicular to each other as shown