State Lenz Law Of Induced Emf ?
Lenz’s law states that, whenever an emf is induced, the induced current is in such a direction as to oppose (by its magnetic action) the change inducing the current. Lenz’s law is a particular example of the principle of conservation of energy. An induced current can be produced heat to do chemical or mechanical work. The work energy must come from the work done to the motion of a magnet or a coil, work is done; therefore the motion must be resisted by a force. This opposing force comes from the action of the magnetic field of the induced current. When a change in current in a primary coil induces an emf in a neighboring secondary coil, the current in the secondary will be in such a direction as to require the expenditure of additional energy in the primary to maintain the current.
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.
