hello sir,how lenz's law is the consequence of conservatiopn of energy,i want the detail explanation.

Lenz's Law

An electric current that is induced by a changing magnetic field will in turn induce its own magnetic field. According to Lenz's law, the induced electric current must be in such a direction that the magnetic field induced by the current opposes the original cause of the induced current.

Lenz's Law and Conservation of Energy

Lenz's law is a consequence of the law of conservation of energy. According to the law of conservation of energy the total amount of energy in the universe must remain constant. Energy can be neither created nor destroyed. Hence it is impossible to get free energy from nothing.

Think about this experiment similar to Faraday's original experiment. Push a bar magnet through a coil of wire. The moving magnet induces an electric current in the wire, which in turn induces its own magnetic field. According to Lenz's law, the induced magnetic field opposes the cause, which is the moving magnet. Hence the induced magnetic field is in a direction to try to stop the moving magnet. If this were not the case, the induced magnetic field would increase the magnet's velocity and thereby increase its kinetic energy. There is no source for this energy. So if the induced magnetic field helped rather than opposed its cause, conservation of energy would be violated.

The connection between Lenz's law and the conservation of energy is a good example of the unity of physics. Many laws stem from a few very fundamental principles.

Read more: http://www.launc.tased.edu.au/ONLINE/SCIENCES/physics/Lenz%27s.html

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Regards

Ramesh