the couple per unit twist of the suspension is equal to what?
Answers
Explanation:
A moving coil galvanometer is an instrument which is used to measure electric currents. It is a sensitive electromagnetic device, which can measure low currents even of the order of a few microamperes.
Moving Coil galvanometer
The moving coil galvanometer has a rectangular coil that has many turns and it is usually made of thinly insulated or fine copper wire that is wounded on a metallic frame. The coil is free to rotate about a fixed axis. A phosphor-bronze strip is connected to a movable torsion head. This is used to suspend the coil in a uniform magnetic field.
In order to improve the strength of the magnetic field and to make the field radial a soft iron core is placed inside the coil The lower part of the coil is attached to a phosphor-bronze spring having a small number of turns. Binding screws are connected at the other end of the spring.
A steady angular deflection is produced by the spring to produce a counter torque which balances the magnetic torque. A plane mirror which is attached to the suspension wire, along with a lamp and scale arrangement is used to measure the deflection of the coil. Zero-point of the scale is at the centre.
The deflection or twist θ of the moving coil galvanometer is measured as the value indicated on a scale by a pointer which is connected to the suspension wire.
θ= ( nAB / k)I
Therefore, θ ∝ I
The quantity nAB / k is a constant for a given galvanometer.