Physics » Electromagnetic Induction and AC Circuits » Faraday’s Law of Induction: Lenz’s Law

# Summarizing Faraday’s Law of Induction

## Summary

• Faraday’s law of induction states that the emfinduced by a change in magnetic flux is

$$\text{emf}=-N\cfrac{\Delta \Phi }{\Delta t}$$

when flux changes by $$\Delta \Phi$$ in a time $$\Delta t$$.

• If emf is induced in a coil, $$N$$ is its number of turns.
• The minus sign means that the emf creates a current $$I$$ and magnetic field $$B$$ that oppose the change in flux $$\Delta \Phi$$ —this opposition is known as Lenz’s law.

## Glossary

the means of calculating the emf in a coil due to changing magnetic flux, given by $$\text{emf}=-N\cfrac{\mathrm{\Delta \Phi }}{\mathrm{\Delta t}}$$