Magnetism

Chinese as early as 121 AD knew that an iron rod which had been brought near one of these natural magnets would acquire and retain the magnetic property

magnetite (also called lodestone)

HeadphonesSpeakersPhone ringersSeal around refrigerator doorAudio tape recording and playback headVideo tape recording and playback headCredit card magnetic stripComputer monitor Computer hard drivePower supply transformersRefrigerator magnetsTelephone receivers

FANS…bathroom, ceilingElectric toothbrushGarage door openerCell phone vibratorClocks and Watches

High Speed Trains

WHERE DO YOU FIND OR USE MAGNETS?

Magnets

o magnetism – force of attraction or magnetism – force of attraction or repulsionrepulsion

not all objects are affected by the force of magnetism

ex. wood, glass, paper, plastic

common metals affected by magnetism are ironiron, , nickelnickel, and , and cobaltcobalt

Magnets

poles – two ends of a magnetpoles – two ends of a magnetevery magnet has two poles

• north (N) pole AND south (S) polenorth (N) pole AND south (S) pole even if you break a magnet in half, each half will

have a north pole and a south pole.

Properties of Magnets

like magnetic poles repel like magnetic poles repel each other

unlike magnetic poles attract unlike magnetic poles attract each other

Magnetic Fields

magnetic field – area around a magnet magnetic field – area around a magnet where magnetic forces can act.

Making a Magnet

a material that is easily magnetized tends to lose its magnetism quickly

a magnet made of this kind of material is called a temporary magnet

Making a TEMPORARY Magnet….An Iron Nail made up of atoms have all electrons

spinning in different directions……by rubbing a magnet over the nail in one direction will get the electrons to

SPIN all in the SAME direction..

This makes the nail into a temporary magnet.

Electromagnets

electromagnet – temporary magnet electromagnet – temporary magnet made by wrapping a current-carrying wire around an iron core the center of an electromagnet is called the

core and is often made of iron.

Electromagnets

there are two ways to make an electromagnet stronger

increasing the number of coils

increasing the amount of current or voltage

Electromagnets

as long as current is flowing, an electromagnet has a magnetic field

electromagnets are useful because they can be turned on and off.

electromagnets have many important usesex. radios, telephones, computers

The Earth as a Magnet

William Gilbert

a British scientist

The Earth as a Magnet

the Earth has a North Magnetic Pole and a South Magnetic Pole

The earth is like a giant magnet!The nickel iron core of the earth gives the earth a

magnetic field much like a bar magnet.

The Earth as a Magnet

magnetosphere – region of the Earth’s magnetic field

The Earth as a Magnet

the magnetosphere traps charged particles from the sun

auroras are also called the northern lights

NOW….FUN with Magnets

Continue in your notebook my drawing….

How to make a temporary magnet. How to make an electromagnet. North/North Poles with iron filings North/South Poles with iron filing Lines of force between magnets

Magnets and ELECTRICTIY?

Today we look at how magnets are used to create electricity.

In the early 1800s, Michael Faraday discovered “electromagnetic induction” – the scientific way of saying that if he moved a magnet through a loop of wire, the wire would become electrified.

a little bit later…….

In 1882, Thomas Edison opened the first full-scale power plant in New York City. Edison’s electric generator was a bigger version of Faraday’s basic experiment – a big magnet rotates around a wire to produce an electric current.

Today’s power plants are bigger and controlled by computers, but the basic process is still the same as it was nearly 120 years ago.

Generators

Electricity

A wire passes through a magnetic field A wire passes through a magnetic field will move the electrons in a wire in an will move the electrons in a wire in an alternating motionalternating motion.

Electric Motors

an electric motor is made up of an electromagnet and a permanent magnet

Electricity

This is called.. Electromagnetic Induction This is called.. Electromagnetic Induction

Or ELECTRICITYOr ELECTRICITY

How do you turn a Generator?

How do you turn a Turbine?

We convert other forms of energy into We convert other forms of energy into Thermal energy (STEAM) to spin the turbineThermal energy (STEAM) to spin the turbine

It’s all about the STEAM!

A Power Plant….

Types of Power Plants

COALNatural GasOilNuclearHydropowerWind PowerSolarGeothermal