9. The working principle of galvanometer is based upon

The working principle of a galvanometer is based on the principle of electromagnetic deflection. Here are the steps explaining how it works:

1. A galvanometer works on the principle that a current-carrying coil rotates in a magnetic field. This is known as the electromagnetic deflection principle.

2. The galvanometer consists of a coil of wire wound on a metal frame. This coil is suspended between the poles of a powerful magnet.

3. When an electric current is passed through the coil, it generates a magnetic field around it.

4. This magnetic field interacts with the magnetic field of the permanent magnet. As a result, a torque (or force) is exerted on the coil, causing it to rotate.

5. The rotation of the coil is proportional to the current passing through it. The greater the current, the greater the rotation.

6. The rotation of the coil is measured by a pointer attached to it. The pointer moves over a calibrated scale, providing a reading of the current.

7. A spring attached to the coil provides a restoring force that opposes the rotation of the coil. This ensures that the coil stops rotating when the current is removed, and returns to its original position.

8. The deflection of the pointer is directly proportional to the current passing through the coil. Therefore, by observing the deflection, one can measure the current.

9. The galvanometer can also be used to measure voltage by connecting it in parallel with the circuit element. The deflection of the pointer will then be proportional to the voltage across the circuit element.