Download MAGNETIC FORCE

MAGNETIC FORCE
PHYSICS WITH TECHNOLOGY
Magnetic Force vs. Electric Force
 ELECTRIC
 BOTH
 Two charges:
 Likes repel
Positive and
negative
 Charges can
exist
separately
 Affects ALL
metals
 Opposites
attract
 MAGNETIC
 Two Poles:
North and
South
 Poles
ALWAYS
come as a
pair
 Only affects
some metals
(iron)
Unification
 Unification:

They used to think there were two separate forces:
electric and magnetic.

We now know they are linked: Electromagnetic force.
What causes Magnetism?
 If all the electrons spin the same direction then an
object is a magnet.
 If all the electrons can be taught to spin the same
direction then an object will stick to a magnet. (call
this ferroumagnetic in honor of iron=ferrous)
 (Has to do with p orbitals in chemistry).
Magnetic Fields
 Rules:
1.
Arrows point OUT of North pole and INTO South
pole
2. Arrows NEVER cross.
Magnetic Fields
Electromagnetic Link:
 Hans Oersted: Moving charges generate magnetic
fields.
 Michael Faraday: Moving magnets generate electric
fields.
 James Maxwell: Developed 4 famous equations that
unite electricity and magnetism.
Electromagnetic Induction
1.
When electric charges move it generates a magnetic
field (you can make a magnet using electricity).
2. When magnets move it generates an electric field
(you can use magnets to make electricity).
ELECTROMAGNETS
 What are they?
Man-made magnets powered by electricity
 Why are they better than natural magnets?
You can turn them on and off. They are not heavy.
 How do you make one?
Wrap a coil of wires around an iron object. Put
electricity through the wire.
 Where do you find them?
Speakers, ear phones, telephones, wrecking yards
GENERATOR
 What are they?
Use magnets to generate electricity.
 How do you make one?
Spin a coil of wires inside a magnet.
 Where do you find them?
Power plants, camping, emergency back up
devices.
POWER PLANTS
 Step 1: Get a large blade called a turbine to spin in circles
 Step 2: Use the turbine to spin a large coil of wires.
 Step 3: Place the wire coil inside a giant magnet.
 How do you get the blade to spin in the first place?
Steam pressure, running water, or wind.
 Do all power plants use generators?
No. Solar panels use chemical energy like a battery
does.
MOTOR
 What are they?
Use electricity to make a magnet spin.
 How do you make one?
Run electricity through a coil of wires near a magnet.
 Where do you find them?
Toy cars, blenders.
 Are they the same thing as an engine?
No. Engines burn fuel. Motors do not.