2 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
3 Magnetic poles and fields Magnets always have two polesIf a magnet is cut it will still have two polesLike magnetic poles repelUnlike magnetic poles attractA magnetic field is the area in which magnetic forces act
4 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.
5 Magnetic materialsNatural magnets have naturally occurring magnetic properties ex: LODESTONE (magnetite)
6 Temporary magnetsEasy to magnetizeLose their magnetism quicklyEx: Soft iron
7 Permanent magnetsHard to magnetizeStay magnetized longer than temporary magnetsEx: alnico (cobalt, nickel, aluminum)
8 QuestionsHow is a temporary magnet different from a permanent magnet?Give an example of a natural magnet.
9 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
10 Compasses Compasses are used to determine direction Compass needles are magnetized and respond to the magnetic field of the EarthCompasses point to the MAGNETIC POLES OF THE EARTH
11 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
12 Questions Which scientist described the Earth’s magnetic properties? Name the devices used to indicate geographic direction based on the Earth’s magnetic field.
13 QuestionsWhat is the name of the Earth’s magnetic field?Where is the Earth’s magnetic field the strongest?
14 Magnetic variationMagnetic poles of the Earth are different from the geographic poles of the Earth
15 Magnetic InductionProcess by which materials can be magnetized
16 What affects magnetic properties? Spinning electrons cause some metals to have magnetic propertiesMagnetic domains are groups of arranged magnetic fieldsDropping,hammering or heating a magnet will cause a magnet to lose magnetic properties
17 Electromagnetism Discovered by Oersted (scientist) Relationship between electricity and magnetism
18 Electromagnets Temporary magnets Magnetism can be turned on and off Made 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
19 Increasing the strength of electromagnets Increasing the voltage or currentIncreasing the number of loops of wire
20 Questions Explain 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?
21 Electric motors vs. generators Electric motors convert electricity to mechanical energy in order to do workGenerators convert mechanical energy to electrical energy
22 Transformers Used to increase or decrease voltage Made of primary and secondary coilsTwo types of transformers:“Step-up” (increase voltage)“Step-down”(decrease voltage)
23 Questions How 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?