Describe Induced Emf And Currents ?
Consider coil of wire connected to a sensitive galvanometer G. if the N pole of a bar magnet is thrust into the coil, the galvanometer will deflect, indicating a momentary current in the coil in the direction specified by the arrows. This current in called an induced current and the process of generating the emf is known as electromagnetic induction. As long as the bar magnet remains at rest within the coil, no current in induced. If, however, the magnet is quickly removed from the coil, the galvanometer will indicated a current in the direction. Opposite that at emf is induced when there is any change of magnetic flux linked by the conductor.An emf may also be induced in a coil by the change in the magnetic field associated with a change in current in a nearby circuit. For example, a coil M connected to a battery through switch S. A second coil N connected to a galvanometer is nearby. When the switch S is closed, producing a current in the coil M in the direction shown, a momentary current is induced in coil N in a direction (arrow a) opposite to that in M. if S is now opened, a momentary current will appear in N, having the direction of arrow b. in each case there is a current in N only while the current is M is changing. A steady currents in M accompanied by a motion of M relative to N is also found to induce a current in N. we observed that, in all cases in which a currents is induced in N, the magnetic flux through N is also changing.
