Question

The following diagram in figure shows a coil of several turns of copper wire near a magnet NS. The coil is moved in the direction of the arrow shown in the diagram. How would the current in the coil be altered if the coil was made to move three times as fast?

                            

Answer 1

Hint The value of current flowing in the circuit is directly proportional to the velocity of the moving magnet or coil. Because, the flux associated with the loop changes faster when velocity is more this induces more current.

Complete step-by-step answer

According to Lenz's law, the direction of the induced emf or current in the circuit is such that it opposes the cause that produces it. This law is based on the conservation of energy.

When the north pole of the magnet moves towards the coil, the flux associated with the loop increases and current is induced. As the circuit is closed, the current induced flows in it.

If the speed of the magnet increases then induced emf or the current also increases but the induced charge remains the same. The same happens even if the coil is moved. So, the coil here moves three times faster, the rate of change in the flux is also faster making the current flowing through the circuit three times more its initial value.

Note When the magnet is moved in the opposite direction the current is still induced but in the opposite direction. The same observations are made when the south pole of the magnet is moved towards or away from the coil. The direction and motion is completely relative and depends on the position of the observer.