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Review: Magnetic Fields and Electromagnetic Induction

Physics Chapters 24 & 25. Review: Magnetic Fields and Electromagnetic Induction. True or False: Magnetic field lines form closed loops. Answer: True. Which of these materials are used to make permanent magnets: a) neodymium b) gadolinium c) ALNICO V d) all of the above Answer: d.

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Review: Magnetic Fields and Electromagnetic Induction

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  1. Physics Chapters 24 & 25 Review: Magnetic Fields and Electromagnetic Induction

  2. True or False: Magnetic field lines form closed loops. Answer: True

  3. Which of these materials are used to make permanent magnets: a) neodymium b) gadolinium c) ALNICO V d) all of the above Answer: d

  4. True or false: Electromagnets are useful because they can easily be turned on and off. Answer: T

  5. True or False: When a magnet is allowed to swing freely, it comes to rest aligned in the north-south direction. Answer: True

  6. True or false: In a motor, mechanical energy is used to produce electric current. Answer: F - generator

  7. A small magnet mounted so it is free to turn a) galvanometer b) compass Answer: b

  8. True or False: Hans Christian Oersted discovered that electric current creates a magnetic field. Answer: True

  9. True or false: The iron core is included in an electromagnet because it is a good conductor. Answer: F – the iron core is included because it is easily magnetized and thereby enhances the magnetic field of the coil.

  10. True or False: Increasing the current in a wire increases the magnetic field around the wire. Answer: True

  11. True or False: The magnetic field strength of a magnet is weakest at the poles. Answer: False

  12. An electromagnet is a a) temporary magnet b) permanent magnet Answer: a

  13. True or false: Voltage can be reduced with a step-up transformer. Answer: false – step-down transformer

  14. True or False: Increasing the number of loops of wire in an electromagnet increases the strength of its electric field. Answer: True

  15. True or False: Magnets may be monopoles. Answer: False

  16. True or false: An electromagnet consists of a current-carrying wire coil surrounding an iron core. Answer: T

  17. Having two distinct and opposite ends a) magnetic flux b) polarization Answer: b

  18. What is a vector quantity that exists in a region of space where a magnetic force occurs? a) magnetic field b) magnetic flux Answer: a

  19. True or false: Maglev is short for magic levitating train Answer: false – magnetic levitating train

  20. True or false: Magnetic field lines show the direction and shape of the magnetic field around a magnet. Answer: T

  21. What does a transformer transform? a) voltage b) charge Answer: a

  22. A magnet created when current flows through a wire coil a) solenoid b) electromagnet Answer: b

  23. A group of neighboring atoms that have their magnetic fields aligned in the same direction a) polarization b) domain Answer: b

  24. True or False: Michael Faraday discovered that changing magnetic fields create electric current. Answer: True

  25. A device to measure very small currents a) galvanometer b) electromagnet Answer: a

  26. True or False: The earth’s geographical north pole is near its magnetic south pole. Answer: True

  27. True or false: Magnetic forces or fields are produced by stationary electric charges. Answer: F

  28. True or False: Magnetic field lines point from south to north. Answer: False

  29. True or false: Motors and generators both use an electromagnet to change energy from one form to another. Answer: T

  30. True or false: In a step-down transformer, the primary coil has more loops than the secondary transformer. Answer: T

  31. True or false: Moving magnets produce electric forces or fields. Answer: T

  32. True or false: Junk yard electromagnets work because current is flowing through a wire coil. Answer: T

  33. A long coil of wire consisting of many loops a) solenoid b) galvanometer Answer: a

  34. True or false: In a generator, electrical energy is used to produce mechanical energy. Answer: F - motor

  35. True or false: Electricity and magnetism are two aspects of the same force. Answer: T

  36. Swiping your credit card allows a magnetic strip on the back to pass a wire coil. What principle explains this process? a) Electric current creates a magnetic field. b) A changing magnetic field produces an electric current. Answer: b

  37. True or False: Like poles attract and opposites repel. Answer: False

  38. True or false: Generators produce electrical current by placing a wire coil in a changing magnetic field. Answer: T

  39. The number of magnetic field lines passing through a surface a) magnetic flux b) domain Answer: a

  40. Maglev trains can achieve such high speeds because they are a) floating on a cushion of air b) aerodynamic c) both Answer: c

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