Lenz’s law

Definition

Lenz's Law states that the direction of an induced electric current will oppose the change in magnetic flux that caused it. This is a consequence of the conservation of energy.

5 Must Know Facts For Your Next Test

1. Lenz's Law is mathematically represented as $\mathcal{E} = - \frac{d\Phi_B}{dt}$, where $\mathcal{E}$ is the electromotive force (emf), and $\Phi_B$ is the magnetic flux.
2. It ensures that induced currents create magnetic fields opposing the original change in magnetic flux.
3. Lenz's Law can be demonstrated using Faraday's law of electromagnetic induction.
4. This law explains why a moving magnet induces a current in a coil and why this induced current creates its own opposing magnetic field.
5. The negative sign in Lenz's Law equation indicates the direction of the induced emf opposes the change in magnetic flux.

Review Questions

• How does Lenz’s Law relate to conservation of energy?
• What does the negative sign in Lenz’s Law equation signify?
• Can you describe a real-world example demonstrating Lenz’s Law?

Related terms

Faraday's Law of Induction: States that a changing magnetic field within a closed loop induces an electromotive force (emf) proportional to the rate of change of the magnetic flux through the loop.

Magnetic Flux: A measure of the amount of magnetic field passing through a given surface area, typically measured in webers (Wb).

Electromotive Force (emf): The potential difference generated by either electrochemical or electromagnetic means, which drives an electric current around a circuit.