Magnetism

What is magnetism?

Force of attraction or repulsion due to electron arrangementMagnetic forces are the strongest at the polesMagnets have two poles: North and South

Magnetic poles and fieldsMagnets always have two polesIf a magnet is cut it will still have two polesLike magnetic poles repel Unlike magnetic poles attractA magnetic field is the area in which magnetic forces act

QuestionsWhat two forces are involved in magnetism?Which subatomic particle accounts for magnetism?Explain the interaction between magnetic poles when they are close together.

Magnetic materials

Natural magnets have naturally occurring magnetic properties ex: LODESTONE (magnetite)

Temporary magnets

Easy to magnetizeLose their magnetism quicklyEx: Soft iron

Permanent magnets

Hard to magnetizeStay magnetized longer than temporary magnetsEx: alnico (cobalt, nickel, aluminum)

Questions

How is a temporary magnet different from a permanent magnet?Give an example of a natural magnet.

Earth’s magnetic properties

Gilbert was a scientist that showed that the Earth behaves as a magnetThe Earth’s magnetic field is strongest at the polesEarth’s magnetic field is called the magnetosphere

CompassesCompasses are used to determine directionCompass needles are magnetized and respond to the magnetic field of the EarthCompasses point to the MAGNETIC POLES OF THE EARTH

Other sources of magnetism

Magnetic fields of the Earth and other planets are related to their coresThe sun is a source of a magnetic field

Questions

Which scientist described the Earth’s magnetic properties?Name the devices used to indicate geographic direction based on the Earth’s magnetic field.

Questions

What is the name of the Earth’s magnetic field?Where is the Earth’s magnetic field the strongest?

Magnetic variation

Magnetic poles of the Earth are different from the geographic poles of the Earth

Magnetic Induction

Process by which materials can be magnetized

What affects magnetic properties? Spinning electrons cause some

metals to have magnetic propertiesMagnetic domains are groups of arranged magnetic fields Dropping,hammering or heating a magnet will cause a magnet to lose magnetic properties

Electromagnetism

Discovered by Oersted (scientist)Relationship between electricity and magnetism

ElectromagnetsTemporary magnetsMagnetism can be turned on and offMade by wrapping wire around a piece of iron and sending a current through the wireMagnetic field is in the same direction as the electric current

Increasing the strength of electromagnets

Increasing the voltage or currentIncreasing the number of loops of wire

QuestionsExplain magnetic variation.What is electromagnetism?Who discovered electromagnetism?Name two ways to increase the strength of an electromagnet.What type of magnet is an electromagnet?

Electric motors vs. generators

Electric motors convert electricity to mechanical energy in order to do workGenerators convert mechanical energy to electrical energy

TransformersUsed to increase or decrease voltageMade of primary and secondary coilsTwo types of transformers:“Step-up” (increase voltage) “Step-down”(decrease voltage)

QuestionsHow is a generator different from an electric motor?Name two types of transformers.How is a step-up transformer different from a step down transformer?What are the two parts of a transformer?