Unit 8 Magnetism

Permanent Magnets

Permanent magnet– naturally magnetic

materials– iron, cobalt, and nickel

Magnetic Properties

Poles (north and south)

If you chop them in half, each half still has a N and S pole

– Like poles repel

– Opposite poles attract

What makes materials magnetic?

•Groups of atoms that have aligned electrons are called domains

•domains are aligned in permanent magnets

Magnetic Field

Every magnet creates a magnetic field in the space around it

This is how magnets have forces between them without even touching

Electromagnets

– an electrical current passes through a coil of wire wrapped around some iron

– more current, stronger magnet

– Can be turned on and off

Electromagnetic induction

– Flowing current induces a magnetic field

– a moving magnet induces electrical current to flow

Electric Motor

converts electrical energy into mechanical energy

A current causes an electromagnet to rotate

Electric Generators

Converts mechanical energy into electrical energy

A coil of wire rotates within a magnetic field-generates a current

Generator simulation

Making electricity

Begin with fuel (chemical energy- fossil fuels) or another form of energy (nuclear, solar, hydro)

Convert from one form of energy into mechanical energy (turn turbine- large fan)

Turbine will rotate a magnet in a coil of copper wire (generator!!)

Electrons flow in the wire…viola..electricity

Energy conversion

Transmitting electricity

Increase voltage for travel

Decrease voltage when at your home

Use transformer – electrical device that changes voltage