Galvanometer

definition

Construction of a moving coil galvanometer

The galvanometer consists of a coil, with many turns, free to rotate about a fixed axis, in a uniform radial magnetic field. There is a cylindrical soft iron core which not only makes the field radial but also increases the strength of the magnetic field.When a current flows through the coil, a torque acts on it.The magnetic torque tends to rotate the coil. A spring provides a counter torque that balances the magnetic torque, resulting in a steady angular deflection. The deflection is indicated on the scale by a pointer attached to the spring.

definition

Working principle of the moving coil galvanometer

When a current flows through the coil, a torque acts on it. The magnetic torque  tends to rotate the coil. A spring provides a counter torque that balances the magnetic torque resulting in a steady angular deflection

example

Tangent coil galvanometer

In a tangent galvanometer, the circular coil is unwound and rewound to have twice the previous radius. As a result of this, find the reduction factor of the tangent galvanometer.
and also no. of turns are halved


becomes times larger