Lenz's Law Demonstration - Interactive Simulation

Interactive demonstration of electromagnetic induction and Lenz's law with coil, magnet, and galvanometer visualization

Magnetic Flux: 0.00 mWb
Induced EMF: 0.00 mV
Induced Current: 0.00 mA
Magnet Position: 0.00 cm

Galvanometer

-I 0 +I
Current Direction: No Current

Magnetic Flux vs Time

Induced EMF vs Time

Induced Current vs Time

Parameters

Physical Equations

Magnetic Flux: Φ = ∫B·dA = B·A·cos(θ)
Faraday's Law: ε = -N·dΦ/dt
Ohm's Law: I = ε/R
Lenz's Law: ε opposes Φ change

Display Options

What is Lenz's Law?

Lenz's law states that the direction of the induced current is such that it opposes the change in magnetic flux that produced it. This is a consequence of the conservation of energy and is expressed in Faraday's law of induction by the negative sign: ε = -N·dΦ/dt.

Magnetic Flux (Φ)

Magnetic flux is a measure of the number of magnetic field lines passing through a given area. For a uniform magnetic field B perpendicular to a surface of area A, the flux is Φ = B·A. When the angle between B and the surface normal is θ, the flux becomes Φ = B·A·cos(θ).

Faraday's Law of Induction

Faraday's law states that a changing magnetic field induces an electromotive force (EMF) in a conductor. The induced EMF is proportional to the rate of change of magnetic flux: ε = -N·dΦ/dt, where N is the number of turns in the coil. The negative sign represents Lenz's law.

Lenz's Law Explained

When a magnet is inserted into a coil, the magnetic flux through the coil increases. According to Lenz's law, the induced current creates a magnetic field that opposes this increase. The induced current flows in a direction such that its magnetic field opposes the change. When the magnet is extracted, the flux decreases, and the induced current reverses direction to try to maintain the flux.

Applications

Lenz's law is fundamental to many electrical devices including transformers, electric generators, induction motors, electromagnetic braking systems, metal detectors, and wireless charging technology. It explains why eddy currents are created in conductors moving through magnetic fields and how these currents can be used for braking or heating.