Lenz's Law

on . Posted in Electromagnetism

Lenz's law, abbreviated as $$\epsilon$$, is a fundamental principle in electromagnetism that describes the direction of an induced electromotive force (emf) or current in a conductor when it is exposed to a changing magnetic field.  This law is a consequence of the law of conservation of energy and the Faraday's law of electromagnetic induction.  It states that the direction of the induced current in a conductor is such that it creates a magnetic field that opposes the change in magnetic field causing it.  In other words, when a conductor is exposed to a changing magnetic field, the induced current will flow in a direction that creates a magnetic field that opposes the change in the original magnetic field.

Lenz's law can be summarized by the statement, "An induced current or emf always opposes the change that produced it."  This law is based on the principle that work must be done to induce an electric current, and the induced current produces an opposing magnetic field that tries to counteract the change in the original magnetic field.

Lenz's law finds applications in various electromechanical devices, such as electric generators and transformers.  It helps ensure that energy is conserved and that mechanical systems experience resistance when interacting with changing magnetic fields, preventing potential damage or instability.

Lenz's Law formula

$$\epsilon = - N \; ( \partial \Phi_B \;/\; \partial t )$$     (Lenz's Law)

$$N = - \;( \epsilon \; \partial t \;/\; \partial \Phi_B )$$

$$\partial \Phi_B = - \;( \epsilon \; \partial t \;/\; N )$$

$$\partial t = - \;[ \; \partial \Phi_B \;/\; ( \epsilon \;/\; N )\; ]$$

Symbol English Metric
$$\epsilon$$  (Greek symbol epsilon) = induced EMF $$V$$  $$V$$
$$N$$ = number of turns in coil $$dimensionless$$
$$\partial \Phi_B$$ = change in magnetic flux $$Wb$$ $$Wb$$
$$\partial t$$ = change in time $$sec$$ $$s$$