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).