Question

A coil of insulated wire is connected to a battery. If it is taken to galvanometer, its pointer is deflected, because
A. The induced current is produced
B. The coil acts like a magnet
C. The number of turns in the coil of the galvanometer are changed
D. None of these

Answer 1

A galvanometer is an electromechanical instrument which is used for detecting and indicating an electric current. When no current is flowing through the circuit of the coil, there is zero deflection in the galvanometer.

Complete step-by-step answer:
The working principle of a moving galvanometer is that, when a current- carrying coil is placed in an external magnetic field experiences magnetic torque. The angle through which the coil is deflected due to the effect of the magnetic torque is proportional to the magnitude of current in the coil.
When an electric current is passed through the coil inside the galvanometer, induction of the magnetic field takes place and thus the coil acts like a magnet which experiences torque due to a permanent magnet inside the galvanometer and thus the pointer is deflected.

Therefore, when a coil of insulated wire which is connected to a battery, is taken to a galvanometer. Its pointer would deflect because of the production of induced current.

So, the correct answer is “Option A”.

Additional Information:
A moving coil galvanometer experiences sensitivity which is defined as the ratio of the change in deflection of the galvanometer to the change in current in the coil, i.e. $S = \dfrac{{d\theta }}{{dl}}$
If the instrument shows larger deflection for a small value of current, we can conclude that the sensitivity of the galvanometer is higher.
Factors which affect the sensitivity of a galvanometer are number of turns in a coil, magnetic field strength, area of the coil.

Note: A moving coil galvanometer is a highly sensitive instrument due to which it is used to detect the presence of current in any circuit. By connecting a galvanometer in parallel to low resistance can be used to measure the value of current. And connecting it in series with high resistance can be used to measure the voltage.