Transcript What are magnets?

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)
Headphones
Speakers
Phone ringers
Seal around refrigerator door
Audio tape recording and playback
head
Video tape recording and playback
head
Credit card magnetic strip
Computer monitor
Computer hard drive
Power supply transformers
Refrigerator magnets
Telephone receivers
FANS…bathroom, ceiling
Electric toothbrush
Garage door opener
Cell phone vibrator
Clocks and Watches
High Speed Trains
WHERE DO
YOU FIND
OR USE
MAGNETS?
Magnets
o
magnetism – force of attraction or
repulsion

not all objects are affected by the force of
magnetism


ex. wood, glass, paper, plastic
common metals affected by magnetism are
iron, nickel, and cobalt
Magnets

poles – two ends of a magnet

every magnet has two poles

north (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 each other

unlike magnetic poles attract each other
Magnetic Fields

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
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
uses


ex. 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

generator – device that changes
mechanical energy into electrical energy

a current can be induced in a loop of wire by
spinning the loop inside a magnetic field

due to the changing direction of the wire, an
alternating current is produced
Electricity

A wire passes through a magnetic field
will move the electrons in a wire in an
alternating motion.
Electric Motors

an electric motor is made up of an
electromagnet and a permanent magnet
Electricity
This is called.. Electromagnetic Induction
Or ELECTRICITY

How do you turn a Generator?
How do you turn a Turbine?

We convert other forms of energy into
Thermal energy (STEAM) to spin the turbine
It’s all about the STEAM!
A Power Plant….
Types of Power Plants
COAL
 Natural Gas
 Oil
 Nuclear
 Hydropower
 Wind Power
 Solar
 Geothermal
