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In a lab where there wasn’t much action

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Presentation on theme: "In a lab where there wasn’t much action"— Presentation transcript:

1 In a lab where there wasn’t much action
Two magnets supplied some distraction. So they matched opposite poles And now they’re quite an attraction.


3 Magnets and Magnetism 2000 years ago
Greeks found a material that stuck to iron Found in present day Turkey- that was called Magnesia They called it Magnetite We call it Magnet

4 Properties of Magnets 1. Have two poles 2. Magnets exert forces
3. Surrounded by magnetic fields.

5 Have two poles. North and south poles
Always occur in pairs, there will NEVER be just ONE pole. Magnetic effects are NOT even through the entire magnet- stronger at the ends- these ends are called POLES

6 2. Exert magnetic forces Push or pull exerted by magnets
Force of repulsion Force of attraction How is this similar to electricity????? Like poles: Opposite poles:

7 3. Magnetic Fields Area or region around a magnet where magnetic force exists Unevenly distributed around magnet Strongest at the poles, but exists all around Turn to page 185 in the coach, The closer together the lines are, the stronger the field; the farther apart, the weaker it is. Draw a diagram of magnetic fields into your notes.

8 Finding Magnetic Fields
Brain Pop on Magnets: We’ll also do a magnet lab at some point so you can actually see the fields.

9 Classifying magnetism
Ferromagnetism Iron-cobalt-nickel- and alloys Electromagnetism Made from electricity _____________ Permanent magnets Always stay magnetized Temporary magnets Lose their magnetism

10 Why do you think some things are magnetic while others are not?
Turn to your neighbor and discuss this question. After 1 minute, turn to your other neighbor and share what you just discussed.

11 Why some things are magnetic and some are not…
Depends on the atom Many electrons are randomly moving around to and from various atoms. Sometimes the movement is more arranged. Moving electrons create magnetic fields that tend to line up alike next to each other. Most fields interfere with or cancel each other out, others do not and…

12 Take a look at page 457 (xeroxed packet again)
3. Domains Some atoms group together and line up more north to south- and have stronger magnetic fields. Domains are like tons of mini magnets within a large one. They work equally like one large magnet. Take a look at page 457 (xeroxed packet again)

13 Do you remember? What are the different kinds of magnets? (we talked about 4 yesterday)

14 How are magnets made? It depends on what atoms the material are made of. You can also make a magnet from a non-magnetic metal object. Wipe an iron nail repeatedly the same direction with a bar magnet. This aligns the atoms and domains and creates a stronger magnetic force going in the same direction.

15 OK, let’s try it. After you magnetize the nail, put it near a paperclip. What pole is at the point of the nail? What pole of the paperclip is attracted to the magnetized nail? How do you know?

16 How can we make more magnets?
How about cutting a magnet in half- won’t that leave only either the north pole or the south pole?

17 In summary Answer the review questions on page 458 (xeroxed packet)- that is your ticket out the door.

18 Earth as a Magnet Can be seen as one giant magnet
Acts like there is one huge bar magnet running through the earth’s core. Not really- Earth’s core is too hot for a magnet to be there. The electrons moving at the core creates magnetic force.

19 This is how it works: The inner core is solid due to all the pressure, the outer core is liquid. The liquid outer core flows around as the earth rotates which causes charges to move. This movement of charges (which charges are moving?- electrons, protons, or neutrons) Creates a magnetic north and south pole on the earth-on which it rotates. Magnetic north and south are not exactly geographic N and S, close but not quite.

20 Generators and Transformers
Generator- uses electromagnets to change KE into electrical E, it generates or makes electricity Electrical systems in cars- generators Electric Motor- changes electrical E to Kinetic E Transformers- changes the voltage of the electricity going from the power plant to our houses, changes 3 times, High voltage at the plant, made higher to get it out to the wires, and then decreased before coming into our homes at 120 volts.


22 Magnetism from Electricity
Hans Oersted- 1800’s Found- pass current in wire, caused magnetic field to form around wire Current+Wire= magnetic field

- PRODUCTION/interaction OF A MAGNETIC FIELD BY ELECTRICAL CURRENT The field produced- similar to fields from a bar magnet SOLENOID: coil of wire w/current- this is an electromagnet TAKE A LOOK AT PAGE 186 IN THE COACH

1. Place an iron bar inside the coiled wire 2. Coil the wire tighter/increase the number of loops around the iron bar (Strength of the electromagnet increases as the # of coils increases) 3. Increase the current

25 Examples: Scrap metal magnets, high speed trains, doorbells, washers and dryers, ammeters and voltmeters (instruments used by electricians to detect electrical currents) Anything with a generator has a solenoid. Anything else????

In Summary- 3- things you learned about electromagnetism 2- applications/examples of electromagnetism 1- draw a diagram in your notes of a basic electromagnet- a solenoid RAISE YOUR HAND WHEN YOU ARE DONE

27 If electricity can produce magnetism, can magnets produce electricity?
Is this possible? If electricity can produce magnetism, can magnets produce electricity?

28 Electricity from Magnetism
1831 Michael Faraday (GB) & Joseph Henry (US) Independently answered this question Henry solved first, but Faraday is more widely recognized for this finding. Why do you think Faraday (over Henry) is credited with answering this question?

29 Electromagnetic Induction
NO CONTACT, ELECTRICITY AND MAGNETISM Electricity/electric current is ONLY produced when the magnetic fields were CHANGING Not created with a constant magnetic field or force Was produced when a magnet moved back and forth within a wire coil. The faster it moved, the more electricity.

Very important Used by power plants to produce electricity and to get it to our homes What resources are used by power plants to create electricity from electromagnetic induction?

31 Your ticket out the door:
Name the method/device that creates magnetism from electricity. Name the method and device that makes electricity from magnetism. Which of the following changes kinetic energy to electrical energy? Electric motor or generator?

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