Question

How would you demonstrate that momentary current can be obtained by the suitable use of magnet, a coil of wire and a galvanometer?
A. By moving the magnet towards the coil connected to the galvanometer.
B. By moving the magnet away from the coil connected to the galvanometer.
C. both A & B.
D. Insufficient information.

Answer 1

Hint: We all know that when a magnetic field around a coil is changed, or a magnetic flux is a change, an emf is induced inside the coil, and it is called the induced emf. Similarly, if an electric current flows through the wire, a magnetic field also generates around it.

Complete step by step solution:
Let us suppose there is a magnet and a coil. If there is a relative motion between the coils, then the flux's magnetic lines are associated with the coil changes. If one of the magnet poles is brought towards the coil, then the magnetic flux changes, and an emf is induced inside the coil, and the current starts flowing inside the coil.
Although there is one condition for the current to flow, the circuit must be closed. If the current will start to flow inside the coil, we can see the galvanometer needle's deflection. When the magnet is brought in the opposite direction concerning the previous direction, the needle deflects but in the opposite direction. If the galvanometer, along with the coil circuit, is brought towards the magnet, the same thing happens as the flux will change in the same manner.
Therefore, to demonstrate the momentary current, we can do it by taking the magnet towards the coil connected to the galvanometer and taking a magnet away from the coil and galvanometer.

So, the correct answer is “Option C”.

Note:
The direction of the magnetic force responsible for driving the charge is given by right-hand rule. According to this rule, if your index finger represents the direction of the current flow, the middle finger represents the direction of the magnetic field. The thumb represents the direction of the magnetic force.