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CHAPTER 18 - QUESTIONS 1-3 1. Describe the properties of magnets. 2 poles, exert magnetic force, surrounded by magnetic field 2. Explain why some materials are magnetic and some are not. The arrangement of the atoms (called domains) determine whether an object is magnetic or not. 3. Describe 4 kinds of magnets. Ferromagnets – made of iron, nickel, cobalt, etc. Electromagnets – magnet made by an electric current Temporary Magnets – made from materials that are easy to magnetize – lose magnetism easily Permanent Magnets – difficult to magnetize, but keep magnetism indefinitely CHAPTER 18 - QUESTIONS 4-6 4. Give 2 examples of the effect of Earth’s magnetic field. Poles like a compass needle, Spinning electrons cause movement ; magnetic field 5. If 2 magnets push each other away, what can you conclude about their poles? They carry the same charge. 6. Why are copper and aluminum not magnetic? Their atomic structure does not allow for it. CHAPTER 18 - QUESTIONS 7-9 7. Describe 2 ways a magnet can lose its magnetic properties. Striking it or heating it 8. What are ferromagnets? Magnets made with iron, nickel, or cobalt 9. What do scientists think causes Earth’s magnetic field? The movement of electric charges at Earth’s solid inner core (made of iron and nickel). CHAPTER 18 - QUESTIONS 10-12 10. Identify the relationship between an electric current and a magnetic field. A current carrying wire causes a magnet to move. 11. Compare solenoids and electromagnets. Solenoids: a coil of wire with an electric current running through it. Electromagnet: a magnet that has an electric current attached that can be switched on and off. A solenoid is part of an electromagnet. 12. Describe how electromagnetism is involved in the operation of doorbells, electric motors, and galvanometers. An electric current moves in a solenoid that is attached to a magnetic material . This allows the electric current to move so your doorbell rings, motor runs, and galvanometer to measure the movement. CHAPTER 18 - QUESTIONS 13-15 13. What is electromagnetism? The interaction between electricity and magnetism. 14. What happens to the magnetic field of an electromagnet if you increase the current in the wire? The field gets bigger or stronger. 15. Why does a current carrying wire cause a compass needle to move? The electric current creates a magnet field that exerts a force on the compass needle and causes it to move. CHAPTER 18 – QUESTIONS 16-18 16. What does a galvanometer measure? Current 17. Explain how a magnetic field can make an electric current. The movement in a magnetic field induces (makes it move without touching it) an electric current. 18. Explain how electromagnetic induction is used in a generator. Electromagnetic induction is used to change mechanical energy to electrical energy. CHAPTER 18 – QUESTIONS 19-21 19. Compare step-up and step-down transformers. Stepup increase voltage; Step-down decreases voltage. 20. What was Faraday trying to do in his experiment? Prove that an electromagnet could induce an electric current. 21. What energy change happens in an electric generator? Changes mechanical energy to mechanical energy. CHAPTER 18 – QUESTIONS 22-23 22. What are 3 sources of energy that are used to generate electrical energy? Nuclear reaction, fossil fuels, and wind. 23. What does a transformer do? Increases or decreases the voltage of an alternating current. 24. What is AC and DC? AC = Alternating Current – current travelling in both directions. DC = Direct Current – current travelling in one direction.