Lenz law Definition and 6 Discussions

Lenz's law, named after the physicist Emil Lenz (pronounced ) who formulated it in 1834, states that the direction of the electric current which is induced in a conductor by a changing magnetic field is such that the magnetic field created by the induced current opposes changes in the initial magnetic field.
It is a qualitative law that specifies the direction of induced current, but states nothing about its magnitude. Lenz's law predicts the direction of many effects in electromagnetism, such as the direction of voltage induced in an inductor or wire loop by a changing current, or the drag force of eddy currents exerted on moving objects in a magnetic field.
Lenz's law may be seen as analogous to Newton's third law in classical mechanics.

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  1. J

    Direction of current in smaller loop on the left and on the right

    Lets say the current in the larger loop is counterclockwise. Then it doesn't matter if the smaller loop is to the right or to the left of the larger one, the induced current in it will always be clockwise. The magnetic field due to the smaller loop current always points in the negative...
  2. MPavsic

    Induced EMF in closed loops around bar magnet

    I wonder if there is a way to calculate induced EMF in closed loops around bar magnet, which is traveling with constant velocity v to the right as depicted?
  3. Dustin

    B 4 Questions About Lenz's Law Experiment

    Hello, I have four questions. As it stands now, I don't have the necessary materials to test this myself, which is how I'd prefer to learn the answer. I still plan on doing this experiment for fun once I can acquire the necessary components. This deals with Lenz's Law. My goal is to maximize...
  4. U

    Need explanation about magnetic forces

    Hi, I saw this video and I can't explain why the magnet is propelled to the end of the coil with such a huge force. Can someone explain it in clear terms. I also tried to use Flemings left hand (or right hand) rule but it did not give me a satisfactory answer. Thanks, SM
  5. M

    How does Lenz's law delay coil field collapse in magnetos?

    Perhaps the title of this post is not quite correct because I could not find a way to abbreviate what I am asking. Picture a magneto circuit, where, an alternator is used to generate an AC flux into a primary coil of a ignition coil by means of a magnetic core (the primary is wrapped around the...
  6. Narayanan KR

    Dynamo design with regenerative back mmf

    In the above presented dynamo design, three snapshots taken during three instances during the rotor running. In fig 1 the approaching magnet builds an induced voltage across the coil, however the circuit is still open, hence no current flows. In fig 2 when the rotor reaches TDC (top...