1. ELECTROMAGNETIC INDUCTION Magnetism to electricity

2. E LECTROMAGNETIC I NDUCTION  The production of electricity by magnetism is called electromagnetic induction.  Faraday’s law of electromagnetic induction states:  A changing magnetic field in the region of a closed-loop conductor will induce an electric current.

3. EMF  When a wire moves through a magnetic field not only is a current induced, but an electric potential difference is also induced.  This induced electric potential difference is often called the electromotive force (emf).  An emf and current can only be induced in a wire if the wire moves perpendicular to the magnetic field

4. EMF

5. I NDUCED C URRENT  Faraday discovered that three factors influence the magnitude of the emf and induced current in the wire.  These factors are: 1. velocity of the wire  as the velocity increases, the emf and induced current increase 2. strength of the magnetic field  as the strength of the magnetic field increases, the emf and induced current increase 3. length of the wire in the external magnetic field  As the length of the wire increases, the emf and induced current increase Use pHet Simulation to demo

6. E LECTROMAGNETIC I NDUCTION

7. W HY IS AN INDUCED CURRENT CREATED ?

8. L ENZ ’ S L AW  Lenz’s law : An induced current and emf are in such a direction as to oppose the change that produced them.  In other words, the induced current will create a magnetic force that acts on the wire. The direction of this force is opposite to the direction of the wire’s velocity.

9. L ENZ ’ S L AW

11. Determine the direction of the induced current in the solenoid

12. L ENZ ’ S L AW Will a current be induced in the wire segment shown in the following diagram? Explain your answer.