Magnetism What is magnetism? Force of attraction or repulsion due to electron arrangement Magnetic...
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Transcript of Magnetism What is magnetism? Force of attraction or repulsion due to electron arrangement Magnetic...
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 fields
Magnets 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
Questions
What 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 magnetize
Lose their magnetism quickly
Ex: Soft iron
Permanent magnets
Hard to magnetize
Stay magnetized longer than temporary magnets
Ex: 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 magnet
The Earth’s magnetic field is strongest at the poles
Earth’s magnetic field is called the magnetosphere
Compasses
Compasses 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 cores
The 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 properties
Magnetic 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 current
Increasing 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 voltage
Made of primary and secondary coils
Two 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?