Transcript What is Magnetism?

Electricity & Magnetism
What is magnetism?
Magnetism is the properties and interactions of
magnets
FYI: The earliest magnets were found naturally in the
mineral magnetite which is abundant the rock-type
lodestone. These magnets were used by the ancient
peoples as compasses to guide sailing vessels.
Magnets produce magnetic forces and have magnetic
field lines
What is Magnetism?
 Any material that attracts iron, steel,
cobalt and nickel
 Can be permanent or temporary
Magnetism Basics
Only Certain Types of Materials Exhibit Magnetism
N
S
Magnets can be made in a variety of shapes,
but all magnets have 2 poles
•Opposite poles attract
•North/South or Positive/Negative
•Like poles repel
All magnets have lines of force extending from one pole
to the other in the 3 dimensional space around them
Magnetic Lines of Flux
Magnetic Field
Magnetic lines do not cross
each other.
The lines go from North
to South on the magnet.
N
magnet
S
Magnets Attracting Each Other
N
N
S
Pulling
S
Magnets Opposing Each Other
N
N
Pushing Apart
S
S
What are the characteristics of magnets?
North and south poles
“di”-poles
Break the magnet in half and you will have two
separate magnets
3 dimensional field of attraction
Where does magnetism come from?
 Nature
 Man-made materials from:
Ceramic
Alnico (aluminum, nickel, &
cobalt)
Flexible rubber-like material
 Created using current
(electricity)
Uses for Magnets in Everyday Life
 Cars
Power locks
 Homes
Door bells
Microwaves
TV’s
Refrigerators
Speakers
Electricity
 Schools
Whiteboards
Electricity Basics
Electricity is…..
•
The flow of electrons
•
•
•
•
Things that are good conductors of electricity
have lose electrons
Energy is sent out by batteries and
generators (current electricity)
The shock you can get from rubbing your
feet on the carpet (static electricity)
A bolt of lightning! (static electricity)
All Matter is Made up of Atoms
MATTER
(water, diamond)
ELEMENTS
O
H
(oxygen, carbon)
H
ATOMS
(particles)
12
Atoms
What is an Atom?
The smallest component in all things
Made up of three smaller particles
Protons (+)
Neutrons (no charge)
Electrons (-)
Strive for stability
Charged atom = ion
Opposites Attract
++
Attraction
_ _
 Particles with opposite charges attract each
other.
Static Electricity
The imbalance of
positive and negative
charges
Example: a build up
of negative charges
in a storm cloud will
travel to the ground
in the form of
lightening
Static Electricity
 Start with a doorknob – no charge
 Walk along carpet: strip electrons from carpet that
collect in your body… You become negatively
charged
 Approach the doorknob and the positive charges
move toward you. Negative charges move away.
Static Electricity
 When close enough, the electrons will jump toward the
positive doorknob and ZAP! You’ve been shocked by
static electricity.
Static Electricity
 When close enough, the electrons will jump toward the
positive doorknob and ZAP! You’ve been shocked by
static electricity.
 Now you and the doorknob have the same charge.
Current Electricity
Electric current is the movement of free
electrons from atom to atom
To start the free electrons moving an
electromotive force is needed.
 Generator
 Batteries
References
www.srpnet.com
www.ieee.org
www.coolmagnetman.com/magreview.htm
www.en.wikipedia.org/wiki/Magnets
 www.creativekidsathome.com/science/magnetexp.html
www.howstuffworks.com
www.eia.doe.gov/kids/glossary