Question

Explain the importance of the radial magnetic field inside a moving coil galvanometer.

Answer 1

Hint: In a radial magnetic field torque remains maximum everywhere.Radial magnetic field is that field in which the plane of coil of the galvanometer is parallel to the direction of magnetic field.

Complete answer:
Radial magnetic field is that field in which the plane of the coil of the galvanometer is parallel to the direction of the magnetic field. In a radial magnetic field torque remains maximum everywhere. A moving galvanometer is an instrument which is used to measure electric currents.

The main advantage of using a moving coil galvanometer is that it can measure very low currents that are in order of microamperes $({{10}^{-6}})$. A moving coil galvanometer works on the principle that a current carrying coil placed in a magnetic field experiences a torque.

The main importance of using radial, magnetic field is that maximum torque is obtained and torque is uniform in all the positions of the moving coil galvanometer. The angle between the plane of the coil and magnetic field is zero in every position of coil. As the radial magnetic field is parallel to the coil and provides constant torque, this makes the deflection directly proportional to current and helps to measure the current easily.

Note:If a radial magnetic field is not applied then the relation between current and the angle becomes non-linear and therefore current cannot be measured easily in terms of deflection that is produced in the moving coil galvanometer. SI unit of the magnetic field is Tesla. The moving coil galvanometer measures current of order ${{10}^{-6}}$. The current measured by the galvanometer is denoted by ${{i}_{g}}$.