Lenz's law states that any induced current created by a change in magnetic flux will flow in a direction that opposes the change which created it. This is a consequence of electromagnetic induction and Newton's third law, and is represented by the negative sign in Faraday's law of induction. One example is regenerative braking in hybrid vehicles, where the induced current in the alternator from slowing down the vehicle acts to slow it further through its opposing magnetic field.

1. Lenz’s Law

2. What is it?
• Lenz's law is named after Heinrich Lenz,
and it says:
"An induced current is always in
such a direction as to oppose the
motion or change causing it"

3. Why?
• It’s a way of understanding how
electromagnetic circuits obey Newton’s
Third Law... (For every action there is an
equal and opposing reaction.)
• It is basically just a minus (-) sign added
onto Faraday’s Law.

4. What does it mean?
• In everyday life one of the useful applications is
Regenerative Braking.
• This means that in some hybrid cars, when you
press the brake the alternator is used to
generate electricity which is used to recharge
the battery.
• The induced current through the alternator coil
creates a magnetic field that acts against the
magnetic field of the alternator.
• This creates a braking force which helps slow
the vehicle down.

5. Formula
• The Magnetic Fields Laws (Faraday) are:
ε = - Ν (∆φ/∆t) = - Α (∆B/∆t)
(Ν=number of coils, φ=Flux, t=time,
Α=Area and Β=Magnetic Field Strength)
• The important thing is the minus sign,
which makes it an opposing EMF(ε).

6. Formula
• The Magnetic Fields Laws (Faraday) are:
ε = - Ν (∆φ/∆t) = - Α (∆B/∆t)
(Ν=number of coils, φ=Flux, t=time,
Α=Area and Β=Magnetic Field Strength)
• The important thing is the minus sign,
which makes it an opposing EMF(ε).