Question

Using the alligator clip wires, attach the coil with more loops to the galvanometer. Look carefully at the direction that the wires are turned. The idea here is that you will be moving the pole of a magnet closer to the coil— increasing the magnetic field strength in the vicinity of the coil, which is one way to increase magnetic flux.

Experiment 2: , but move the magnet much faster. What happens to your current (as measured by the meter) as you move the magnet faster? Why? More current means more electrical energy. Where does this “extra” energy come from?

Answer 1

According to the law of electromagnetic induction the voltage produced is equal to the rate of change of magnetic flux with respect to time. As we move the magnetic pole near/far to coil the magnetic flux changes and voltage is induced in it, but this induced voltage as mentioned above also depends upon the rate of change of the magnetic flux. So, if we move the magnet at a faster rate more flux lines would pass through coil in lesser time giving higher rate of change of magnetic flux w.r.t. time which gives higher value of induced e.m.f. thus higher current.

The energy which we put in moving the magnet gets converted into the electrical energy, we have to move magnet against the magnetic force caused by induced current in the coil, this work done against the magnetic force( Generated as per Lenz's law), accounts for energy, the extra energy in moving magnet at a faster speed i.e. increase in kinetic energy accounts for conversion and appearance of this energy as extra electrical energy.