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Monday, December 1, 2014

SPS10 . Students will investigate the properties of electricity and magnetism . C. Investigate applications of magnetism and/or its relationship to the movement of electrical charge as it relates to: - electromagnets -simple motors -permanent magnets.

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Monday, December 1, 2014

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  1. SPS10. Students will investigate the properties of electricity and magnetism.C. Investigate applications of magnetism and/or its relationship to the movement of electrical charge as it relates to: -electromagnets -simple motors -permanent magnets

  2. Bell Ringer: What do these items have in common? They all use magnets. • EQ: Draw the magnetic field lines around a permanent magnet. Monday, December 1, 2014

  3. MAGNETISM

  4. Magnets exert FORCES on one another. • How are magnetic forces similar to electrical forces? • They can attract and repel. • Electrical forces: positive and negative charges • Magnetic forces: north and south poles Electricity Vs. Magnetism

  5. Magnetic poles cannot be isolated. How are magnetic forces NOT like electrical forces? http://www.people.vcu.edu/~rgowdy/mod/092/xmp.htm#3

  6. Polarity: north and south poles • Like poles repel, unlike poles attract Characteristics of Magnets

  7. Magnetic domain: cluster of atoms • In an unmagnetized material, the domains are random • In magnetized materials, the domains are aligned Magnetic Domains

  8. Permanent magnets vs. temporary magnets Permanent magnets maintain their magnetic properties for extended periods of time. Temporary magnets can only display magnetic properties when they are used in connection with a permanent magnet.

  9. Field lines spread out from one pole and curve around the magnet to the other pole • Where field lines are close together, magnetic field is stronger. http://micro.magnet.fsu.edu/electromag/java/magneticlines/ Magnetic Fields

  10. Magnetic field lines around a magnet: Out of the north; into the south Magnetic Field Lines

  11. Heating, hitting, or dropping a magnet can cause the domains to get out of alignment Weakening Magnets

  12. GPB Video Magnetism 1001 & 1002

  13. Bell Ringer: What do these items have in common? They all use magnets. • EQ: Draw the magnetic field lines around a permanent magnet. Monday, December 1, 2014

  14. Bell Ringer: What is the difference between a permanent magnet and a temporary magnet? The domains of a permanent magnet are always aligned in the same direction, but they are only aligned in a temporary magnet for a short time. • EQ: Draw the field lines between two north poles. Tuesday, December 2, 2014

  15. What is a magnetic field? • Describe the shape of the magnetic field around two magnets that have like poles facing each other. 3. Describe the shape of the magnetic field around two magnets that have unlike poles facing each other. Magnetism Pre-LabQuestions

  16. Divide your sheet of paper into sections. Magnetism Lab

  17. Tuesday, December 2, 2014 • Bell Ringer: What is the difference between a permanent magnet and a temporary magnet? The domains of a permanent magnet are always aligned in the same direction, but they are only aligned in a temporary magnet for a short time. • EQ: Draw the field lines between two north poles.

  18. Bell Ringer: Label the second pole as N or S. This pattern show repulsion, so the second pole must also be NORTH. • EQ: What three items are needed to create an electromagnet? Thursday, December 4, 2014

  19. Part A: Verifying the Poles of the Magnets • Place the compass on a flat surface and allow its needle to come to a rest. Verify that is does point north. • Pick up one of the bar magnets and bring the pole marked N near the compass. • If the compass needle deflects so that its south pole points toward the N, then that end is in fact the north pole. • Check the end labeled S. It should be attracted to the north pole of the compass. • Verify that both bar magnets have the correct polar orientation. • If the north pole of the bar magnet if instead is attracted to the north pole of the compass, the magnet may be incorrectly magnetized. If this is the case, report the magnet’s condition to your teacher. If both magnets have the correct orientation, then proceed with the experiment. Lab Review

  20. Lab Review • Part B: Magnetic Field Lines • Place one bar magnet on the table and cover it with a blank sheet of paper. • Carefully pour a small amount of iron filings on top of the paper. • Tap the paper lightly with your finger several times until the iron filings form a pattern. • On your paper, draw the magnet, label the poles, and sketch the pattern of the iron filings you see surrounding the magnet. • Carefully pour the iron filings back into the cup.

  21. Lab Review • Part C: Field Lines between the Poles • Place both bar magnets on the table with the north pole of one magnet about 3 centimeters from the north pole of the other magnet. Cover with the blank sheet of paper. • Carefully pour a small amount of iron filings on the top of the paper. • Tap the paper lightly with your finger several times until the iron filings form a pattern. • On your paper, draw the magnets, label the poles, and sketch the pattern of the iron filings you see surrounding the magnets. • Carefully pour the iron filings back into the cup. • Uncover the magnets, and turn one of the magnets around so that the north pole of one magnet is about 3 centimeters from the south pole of the other magnet. Recover with the blank sheet of paper. • Repeat steps 2-5.

  22. Part D: Direction of the Magnetic Field Lines • Lay the small compasses on the table and verify the polarity of each one. (In other words, determine which side of the needles point north.) • Place one bar magnet on the table. • Place the small compasses around the bar magnet and observe the alignment of the compass needles. • On your paper, draw the magnet, label the poles, and sketch the small compasses. Be sure to show the direction each compass points. Lab Review

  23. Part E: Induced Magnetism • Spread out the staples on the table. Be sure they are not hooked together. • Test an iron nail for magnetism by touching it to the staples. On your paper, write down your observations. • Next, hold the nail to one end of a bar magnet. Now bring the nail close to the staples while it is attached to the magnet. On your paper, write down your observations. • With the nail still attached to the magnet, bring the free end of the nail near your compass. On your paper, record your observations. Lab Review

  24. Part F: Magnetic Field Lines • Place one horse shoe magnet and one ring magnet on the table and cover them with a blank sheet of paper. • Carefully pour a small amount of iron filings on top of the paper. • Tap the paper lightly with your finger several times until the iron filings form a pattern. • On your paper, draw the magnets, and sketch the pattern of the iron filings you see surrounding the magnets. • Carefully pour the iron filings back into the cup. Lab Review

  25. Magnetism Lab Discussion Questions 1. Where is a magnet’s magnetic field the strongest? How do the iron filings show this? 2. Describe the magnetic field lines between two like poles. 3. Describe the magnetic field lines between two opposite poles. 4. Describe the orientation of the compass needle compared to the magnet’s poles. 5.Draw a picture of the nail attached to the magnet. Label the North and South poles on the magnet and the nail according to your observations from Part E.

  26. GPB Video Magnetism 100

  27. Is a nail magnetic? • Can a nail become a magnet? • How? • Can a nail become a magnet without a permanent magnet? • How? Inducing Magnetism

  28. A moving current produces a magnetic field. • An electromagnet is made by concentrating the magnetic field that surrounds a wire carrying current. • Three things are needed to create an electromagnet: • Wire • Iron core • Voltage source • Increasing any of the components creates a stronger electromagnet. Electromagnetism

  29. Bell Ringer: Label the second pole as N or S. This pattern show repulsion, so the second pole must also be NORTH. • EQ: What three items are needed to create an electromagnet? • Iron core Coils of wire Voltage source Tuesday, December 10, 2013

  30. Explain the difference between permanent magnets and electromagnets. Electromagnetism Summary

  31. Besides wrapping more coils of wire, name two other ways to increase the strength of an electromagnet. Electromagnetism Summary

  32. Determine whether the magnetic field produced by an electromagnet increases or decreases in each of the following cases: • The number of coils is increased. • The current is decreased. Electromagnetism Summary

  33. What would happen if a wire carrying a current were placed near a compass? Electromagnetism Summary

  34. Electromagnetism Lab Work Session

  35. Yesterday you made an electromagnet which creates magnetism from electricity. Do you think electricity can be created from magnetism? Warmup 12/7/11

  36. Generators • Motors • Transformers http://phet.colorado.edu/ Applications of Electromagnetism

  37. Bell Ringer: Label the second pole as N or S. This pattern show attraction, so the second pole must also be south. • EQ: What energy conversions occur in motor? In a generator? • Motor: electrical to mechanical • Generator: mechanical to electrical Wednesday, December 11, 2013

  38. Magnetic field lines around 2 adjacent magnets: http://micro.magnet.fsu.edu/electromag/java/magneticlines2/

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