Lenz's law (pronounced /ˈlɛntsɨz ˌlɔː/) gives the direction of the induced electromotive force (emf) and current resulting from electromagnetic induction. Electromotive force ( emf, \mathcal{E} is a term used to characterize electrical devices such as Voltaic cells thermoelectric devices electrical Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. Faraday's law of induction describes an important basic law of electromagnetism which is involved in the working of Transformers Inductors and many forms of The law provides a physical interpretation of the choice of sign in Faraday's law of induction, indicating that the induced emf and the change in flux have opposite signs. Faraday's law of induction describes an important basic law of electromagnetism which is involved in the working of Transformers Inductors and many forms of Heinrich Lenz formulated the law in 1834. Heinrich Friedrich Emil Lenz ( February 12, 1804 - February 10, 1865) was a Baltic German Physicist most famous for Year 1834 ( MDCCCXXXIV) was a Common year starting on Wednesday (link will display the full calendar of the Gregorian Calendar (or a Common

Definition

Lenz's law states that the induced current in a loop is in the direction that creates a magnetic field that is parallel to the change in magnetic flux through the area enclosed by the loop. In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges Magnetic flux, represented by the Greek letter Φ ( Phi) is a measure of quantity of Magnetism, taking into account the strength and the extent of a Magnetic That is, the induced current tends to keep the original magnetic flux through the field from changing. This law is an example of Le Chatelier's principle of equilibriums, which also involves a system resisting a change in its original state when disturbed. In Chemistry, Le Chatelier's Principle, also called the Le Chatelier-Braun principle, can be used to predict the effect of a change in conditions on a Chemical

Connection with law of conservation of energy

Lenz's Law is one consequence of the principle of conservation of energy. In Physics, the law of conservation of energy states that the total amount of Energy in an isolated system remains constant and cannot be created although it may To see why, move a magnet towards the face of a closed loop of wire (eg. A magnet (from Greek grc μαγνήτης λίθος " Magnesian stone" is a material or object that produces a Magnetic field. a coil or solenoid). A solenoid is a three-dimensional Coil. In Physics, the term solenoid refers to a loop of wire often wrapped around a Metallic core which An electric current is induced in the wire, because the electrons within it are subjected to an increasing magnetic field as the magnet approaches. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J This produces an emf (electromagnetic field) that acts upon them. The direction of the induced current depends on whether the north or south pole of the magnet is approaching: an approaching north pole will produce an anti-clockwise current (from the perspective of the magnet), and south pole approaching the coil will produce a clockwise current. Polymerase (DNA directed epsilon, also known as POLE, is a human Gene.

To understand the implications for conservation of energy, suppose that the induced currents' directions were opposite to those just described. Then the north pole of an approaching magnet would induce a south pole in the near face of the loop. The attractive force between these poles would accelerate the magnet's approach. This would make the magnetic field increase more quickly, which in turn would increase the loop's current, strengthening the magnetic field, increasing the attraction and acceleration, and so on. Both the kinetic energy of the magnet and the rate of energy dissipation in the loop (due to Joule heating) would increase. The kinetic energy of an object is the extra Energy which it possesses due to its motion Joule heating is the process by which the passage of an Electric current through a conductor releases Heat. A small energy input would produce a large energy output, violating the law of conservation of energy.

This scenario is only one example of electromagnetic induction. Lenz's Law states that the magnetic field of any induced current opposes the change that induces it.

For a rigorous mathematical treatment, see electromagnetic induction and Maxwell's equations. Faraday's law of induction describes an important basic law of electromagnetism which is involved in the working of Transformers Inductors and many forms of In Classical electromagnetism, Maxwell's equations are a set of four Partial differential equations that describe the properties of the electric

Practical demonstrations

A brief video demonstrating Lenz's Law is at EduMation.

A neat device made by William J. Beaty levitates a magnet above two spinning rollers.

A dramatic demonstration of the effect with an aluminium block in an MRI, falling very slowly. WikipediaNaming

A demonstration that even a child can try:
1- Find a small electric motor.
2- Spin its shaft.
3- Connect its wires together (with a paper clip or alligator clip), and spin the shaft again.
4- This time, the motor resists turning, because current can flow through its wires.

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