# Moving Coil Galvanometer

Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics:

Moving Coil Galvanometer:

Galvanometer is used for detecting and measuring small electric currents.

Principle:

Its working is based on the fact that when a current carrying coil is placed in a magnetic field, it experiences a torque.

Construction:

The moving coil galvanometer consists of a coil with a 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 ats on it.

Working:

As terminal are connected (switch on) current flows in the coil and coil start rotating due to torque on it.

If N be the number of turns of the coil with the area A enclosed by a coil, B is the strength of magnetic field, and theta be the angle between coil and magnetic field, then

Sensitivity of Galvanometer:

A galvanometer which on small current shows large deflection is more sensitive.

Learn:- Chhoti Baat ka Bada reaction dena.

Current Sensitivity:

Current sensitivity of galvanometer is the deflection per unit current flowing through it.

Voltage Sensitivity:

Voltage sensitivity is the deflection per unit voltage.