Lenz’s Law

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"

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.

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.

Formula

• The Magnetic Fields Laws (Faraday) are:= - t) = - (B/t)(=number of coils, =Flux, t=time, =Area and =Magnetic Field Strength)

• The important thing is the minus sign, which makes it an opposingEMF.