Induced emf

Definition

Induced emf is the electromotive force generated in a conductor due to a changing magnetic field. It is the principle behind electromagnetic induction and is mathematically described by Faraday's Law.

5 Must Know Facts For Your Next Test

1. Induced emf can be calculated using Faraday's Law: $\text{emf} = -N \frac{d\Phi}{dt}$, where $N$ is the number of turns and $\Phi$ is the magnetic flux.
2. The negative sign in Faraday's Law represents Lenz's Law, indicating that the induced emf opposes the change in magnetic flux.
3. A time-varying magnetic field or relative motion between a conductor and a magnetic field can induce emf.
4. The magnitude of induced emf increases with faster changes in magnetic flux.
5. Applications of induced emf include electric generators, transformers, and inductors.

Review Questions

• How does Lenz's Law relate to the sign of induced emf in Faraday's Law?
• What factors affect the magnitude of induced emf?
• Describe an example where relative motion induces an emf.

Related terms

Faraday's Law: A fundamental law stating that a change in magnetic flux through a circuit induces an electromotive force (emf) proportional to the rate of change of flux.

Magnetic Flux: The measure of the quantity of magnetism, considering both field strength and area through which it passes. It is given by $\Phi = B \cdot A \cdot \cos(\theta)$.

Lenz's Law: $Lenz's Law states that the direction of induced current (and thus induced emf) opposes the change in magnetic flux causing it.$