Question

Explain the Importance of the Radial Magnetic Field in a Moving Coil Galvanometer.

Answer 1

Radial Magnetic Field in a Moving Coil Galvanometer:

1. The radial magnetic field is applied to a moving coil galvanometer to produce a constant torque on the coil.
2. The relation between the current and the angle is measured using this radial magnetic field. Since it is a non-linear field the current cannot be measured easily.
3. The radial magnetic field helps to maintain the angle between the plane of the coil and the magnetic field which is zero in each and every orientation of the coil.

$\therefore \tau =NIAB\sin \theta$

where, $\tau$ is the instantaneous deflecting torque

$N$ is the number of turns present in the coil

$I$ is the instantaneous current through the coil

$A$ is the area of the galvanometer coil

$B$ is a uniform radial magnetic field

$\theta$ is the angle of deflection of the galvanometer.