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.
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.
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. Spring provides a counter torque that balances the magnetic torque resulting in a steady angular deflection.
