Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Magnetism Outline Prepared for BW Physics by Dick Heckathorn 16 April 2 K + 12 1 Table of Contents 1A1 1A2 1B1 1B2 1C1 1E1 1E3 1C1 1D2 How Do Magnets Affect One Another? What metals do magnets attract? Exploring Magnets How can strength of different magnets be compared? Where is a magnet the strongest? How Do Magnets Affect One Another? Where are the poles? Which way is north? Which end of the magnet points north? 2 Table of Contents 1F1 The magnetic Poles of the earth 1F2 A compass needle points toward magnetic north 1G1 What happens when magnets are broken or cut? 1G2 What’s wrong with these pieces of magnets? 1H1 How are magnet particles arranged? 1H2 Magnetic and non-magnetic materials 1H3 How can you make a magnet? 1I1 How can you ‘unmake’ a magnet? 1D2 Which is the Magnet? 3 Learning Station 1 How Do Magnets Affect One Another? 1A1 page 13 4 1A1 Learning Station 1 1. Pick objects of your choice. 2. How are all of the objects which are attracted to the magnet alike? 3. What can you infer about the kind of objects which are attracted to a magnet? 5 All Learning Station 2 What metals do magnets attract? 1A2 page 15 6 Station 1A2 Learning Station 2 paper clip, jar lid, scissors, iron nail, stainless steel spoon, metal bolt, hammer aluminum pie plate, copper penny, lead pipe, brass key, aluminum foil 7 Station 1A2 Learning Station 2 1. In bag A what do all objects have in common? 2. What conclusions can come to? 3. In bag B what do all objects have in common? 8 Station Learning Station 3 Exploring Magnets 1B1 page 17 9 Station 1B1 Learning Station 3 1. Using a paper clip, which objects are magnets and which are not? 10 Station 1B2 Learning Station 4 2. Stick one end of each magnet into a pile of paper clips on the table. See how many clips you can pick up with the magnet. Describe the results. 3. Try testing the strength of the magnets by placing a paper clip on the end of the magnet and making a chain by touching another paper clip on the bottom of the first. 12 Station 1B2 Learning Station 4 4. Test the magnet for the distance through which it will attract a paper clip. 13 Station Learning Station 6 How Do Magnets Affect One Another? 1E1 page 27 16 Station 1E1 Learning Station 6 1. What did you learn? 17 Station 1E1 Learning Station 6 Prediction How would you use a bar magnet with the N and S poles marked to identify a bar magnet that is not marked? 18 Station Learning Station 7 Where are the poles? 1E3 page 33 19 Station 1E3 Learning Station 7 1. Discuss why the magnets behave as they do as you manipulate them one above the other. 20 Station Learning Station 8 Which way is north? 1D1 page 25 21 Station 1D1 Learning Center 8 1. Which way is a magnet orientated when it stops rotation. 2. Suppose you have a bar magnet with the N and S rubbed off. How can you tell which end is the N-Pole and which is the S-Pole? 22 Station 1D2 Learning Center 9 1. Magnets are magnets and behave in a similar manner. 2. Thus, what explanation might one give for the peculiar behavior? 24 Station Learning Station 10 The magnetic Poles of the earth 1F1 page 35 25 Discuss 1F1 Learning Center 10 26 Discuss Learning Station 11 A compass needle points toward magnetic north 1F2 page 37 27 Discuss 1F2 Learning Center 11 28 Station 1F2 Learning Center 11 THE MAGNETIC POLES OF THE EARTH p 36 29 Discuss April 26 30 Learning Station 16 How can you make a magnet? 1H3 page 49 31 Station 1H3 Learning Center 16 WHAT HAPPENS WHEN MAGNETS ARE BROKEN OR CUT? 32 Station 1G1 Learning Station 12 1. Rubbing wire over large magnet causes the wire to _________ . 2. Any way to test your idea? 3. Your results? 33 Demo Learning Station 12 What happens when magnets are broken or cut? 1G1 page 39 34 Demo 1G1 Learning Station 12 1. Bring the wire rubbed on the magnet near a compass. 2. Your results? 3. Cut wire into two pieces. 4. Compass says? 35 Demo Learning Station 13 What’s wrong with these pieces of magnets? 1G2 page 41 36 Discuss 1G2 Learning Station 13 When an iron magnet is broken into pieces, all new pieces of the magnet will retain their polarity. 37 Discuss Learning Station 15 Magnetic and non-magnetic materials 1H2 page 47 40 1H2 Learning Station 15 41 Learning Station 17 How can you ‘unmake’ a magnet? 1I1 page 51 43 Demo Learning Station 17 1. What does the manual suggest as a way to do it? 2. Demonstrate demagnetizer 3. Demonstrate magnetizer. 44 Demo Learning Center 18 Which Is the Magnet? 1I2 page 65 45 Station 1I2 Learning Center 18 46 Station 1I2 Learning Center 18 47 Station How Can You Study a Magnetic Field? 19 2A2 page 57 48 Making A ‘Iron Filings’ Holder 1. 2. 3. 4. Fold the piece of clear plastic in half. Using scotch tape, seal two of the three sides. Have 1/8 teaspoon of steel shot put into the pouch. Seal the 3rd side with tape. 49 Do 1. Place the magnet on the table. 2. Shake the plastic until the spheres are spread out. 3. Place the plastic with spheres on top of the magnet. 50 Do Tap the plastic sheet. a. What happens to the steel spheres as you tap the plastic? b. Describe how the steel spheres are scattered in the plastic? 51 Do 3. Sketch your observations of the steel spheres. Be sure to outline the magnet and label the N and S end. 52 Explanation The pattern is produced by an invisible pattern of magnetic force around the magnet. The space in which magnetism exerts a force is called a magnetic field. 53 Explanation The pattern that we see with the steel spheres are called lines of force. 54 Do 4. Describe the pattern produced by the steel spheres. Where are the greatest and least concentrations of spheres? What does this represent? 55 Do 5. Place a magnet on top of a piece of paper and then outline its position. Push a paper clip from several directions towards the magnet. Mark the spot on the paper where the attraction first occurs. 56 Question 6. How does the pattern of the spheres correspond to the distance at which the paperclip is attracted to the magnet? 57 Question 7. Why doesn’t the magnet need to touch a magnetic object to attract it? 58 Question 8. How can a magnet attract a paperclip without touching it? 59 Conclusion 9. Based on your observations, which is the strongest part of the magnet? Explain. 60 The Magnetic Field Around a Bar Magnet 20 2A3D page 63 61 2A3 Magnetic Field Around a Bar Magnet p 63 62 What is the extent of a magnet’s force? 21 2A1 page 67 63 2A1 1. What was the maximum number of pages between magnet and paper clip? 64 How can you plot a magnetic field? 22 2B1 page 71 65 2B1 A magnetic field surrounds any magnet. The direction of the magnetic field is defined as the direction of the force on a north pole (of a magnet) placed in the field. 66 Magnetic Lines of Force 23 2B2 page 75 67 2B2 68 The Magnetic Field About Two Magnets 24 2B4 page 77 69 Do 1. Lay 2 bar magnets on a flat surface 4cm apart. 70 Do 2. Place the plexiglas with steel spheres on top of the magnets. 71 Do 4. Tap the plastic gently. 72 Do 5. Draw the resulting pattern. 73 The Magnetic Field Between Like Poles 74 Prediction 6. What do you think will happen if you repeat the experiment but with the two magnets farther apart? Try it and then draw your observations. 75 Prediction 7. What do you think will happen if you did the same experiment, but this time, place the North and South Poles of the two magnets 4-cm apart? 76 Prediction 8. Test your prediction. 77 Do 9. Draw your observations. 78 The Magnetic Field Between Unlike Poles 79 Conclusion 10. What do you conclude about the pattern made by the steel spheres when: a. when like poles are near each other? b. when unlike poles are near each other? 80 Show 3-D models 81 The Magnetic Field About Two Magnets 25 2B5 page 87 82 2B5 The magnetic field between unlike poles The magnetic field between like poles 83 2B5 Like magnetic poles repel. Unlike magnetic poles attract. 84 Is it only temporary? 2D1 page 91 85 Final Day 89 Demo: How Are Magnetism And Electricity Related? 3A1 page 97 90 1 6-volt battery 30 cm length of insulated copper wire, stripped 1 cm at ends and 3 cm at center iron filings, fine sheet of paper long wire, green power source, compass 91 Set Up 1. Place the plastic with iron filings on the table. 2. Connect the ends of a copper wire to the terminals of a battery. 3. Tap the plastic with your finger. 92 Do 4. Observe and record what happens. 5. Predict what would happen of the wire is disconnected from the battery. 6. Disconnect the wire from the battery. 93 Do 7. Repeat using paper instead of the steel spheres. 8. Compare results. 94 Infer 8. What can you infer about the relationship between electricity and magnetism? 95 Oersted’s Serpendipity 3A2D page 101 96 Information In the early 1700’s, lightning was observed to change the direction of compass needles. Could it be that there was a relation between electricity and magnetism? 97 Do Lay the current carrying wire on top of a compass. Throw switch. What do you observe? (This Oersted did absent-mindedly.) 98 Do Move the compass at various position relative to the wire and/or move the wire relative to the compass. What do you observe? 99 Observations A current carrying wire will cause a magnet needle to turn. The magnetic field above the wire and beneath the wire are opposite in direction. 100 Conclusion A current-carrying wire is encircled by a magnetic field The magnetic field above the wire and beneath the wire are opposite in direction. 101 Magnetic Field Surrounding A Current Carrying Wire. 3A3D page 103 102 2A3D 103 104 Direction Of Magnetic Field Surrounding A Current-Carrying Wire 3A4D page 107 105 106 Magnetic Field About A Loop Of Current Carrying Wire 3A6D page 109 107 108 Magnetic Field About A Coil Of Current Carrying Wire 3A7D page 111 109 110 111 How Does An Electromagnet Work? 3B1 page 113 112 113 How is a magnet used to detect electricity? 3B5 page 117 114 115 How can a magnet produce electricity? 3C1 page 119 116 117 The Electric Wire Generator 3C2D page 121 118 119 Force on a Wire in B Field Demo 120 Large Motor Demo 121 What makes a motor work? (Making a Motor) 3D2 page 123 122 123 The Motor Generator. 3D3 page 127 124 That’s all there is folks! 125 Demonstration #1 Move a wire through the jaws of a horseshoe magnet. Results? Large magnet – wire – Galvanometer 126 Demonstration #2 Plunge a bar magnet into and out of the core of a coil. Bar magnet – coil – wire – Galvanometer 127 Demonstration #3 theto switch. What Close happens the meter? The two wires are not connected. Anything surprising? Green or large power source – iron ring or my coils - wire – Galvanometer 128 Demonstration #3 Open the switch. What happens to the meter? Green or large power source – iron ring or my coils - wire – Galvanometer 129 Demonstration #3 theto switch. What Close happens the meter? The two wires are not connected. Anything surprising? Green or large power source – iron ring or my coils - wire – Galvanometer 130 Demonstration #3 Open the switch. What happens to the meter? Green or large power source – iron ring or my coils - wire – Galvanometer 131 Demo - Coil 1. Used as Magnetizer 132 Demo - Coil 2. Two Rings – Adjust Height 133 Demo - Coil 3. Induced Voltage 134 Demo - Coil 4. Various Size Coils 135 Demo - Coil 5. Bulb connected to coils 136 Demo - Coil 6. Radio Transmission 137 Demo - Coil 7. Magnetic Braking 138 Demo - Coil 8. Dropping Magnet 139 Demo - Coil 9. Dropping Copper Tube 140 Demo - Coil 10. Ball Magnet 141