physics test

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physics test
2011-03-24 17:55:59
physics test

physics test
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  1. how many poles do all magnets have?
  2. what hapens if a magnet breaks in half?
    each piece becomes a magnet with 2 poles
  3. who discovered that a current-carrying wire caused a compass needle to move?
  4. the domains are aligned in a magnet.
    true or false
  5. what is the right hand rule used to demonstrate?
    the direction of current and magnetic field
  6. what kind of magnets are the strongest ones?
  7. how can alternating current be generated?
    moving a magnet in and out of a coil wire
  8. what is the frequency of alternating current in the U.S.?
  9. can magnetic poles be seperated?
  10. when is the magnetic force on a charged particle or a current-carrying wire the greatest?
    when it's perpendicular
  11. what has a magnetic field in the shape of circles?
    current carrying wire
  12. where is the magnetic field on a magnet the strongest?
  13. if an iron bar is inserted into the center of a solenoid, what happens to the domains in the iron?
    they align
  14. whose law says that the magnetic field of an induced current is opposed by the magentic field that produced it ?
  15. what device converts mechanical energy to electrical energy?
  16. what device converts electrical energy to mechanical energy?
    electric motor
  17. what are the threee ferromagnetic elements?
    iron , cobalt , and nickel
  18. what is the process of inducing an electric current by a changing magentic field?
    elecrotmagnetic induction
  19. what is a device that changes voltage called?
  20. who are the two men that discovered electromagnetic induction was possible?
    Faraday & Henry
  21. What do scientists think causes the earth's magnetism?
    moving currents in the core of the earth
  22. what is produced when charged particles from the sun get caught in the earth's magnetic field?
  23. whose law says that induced voltage is proportional to the number of loops of wire and the rate the magnetic field changes?
  24. what are methods used to generate electricity?
    falling water , sunlight , burning fossil, and nuclear reactions
  25. the area around a magnet where its force is felt is called a ?
    magnetic field
  26. what causes magnetism?
    movement of an electron or charges
  27. what kind of meters can a galvanometer be made in to?
    volmeters and ammeters
  28. what kind of transformer lowers voltage?
    a step-down
  29. what kind of transformer raises voltage?
    a step-up
  30. what kind of current is sold the most today?
    alternating current
  31. which pole of a magnet points toward the geographic north pole?
  32. in what direction are the magnetic field lines drawn around a bar magnet?
    north to south
  33. how can the magnetic field be straighthened around a current carrying wire?
    more coils of wire , more current , or wrap it around a nail
  34. what is one way an iron nail can be made into a magnet?
    attach it to a magnet
  35. what are two advantages of electromagnets?
    you can turn them on and off & more powerful
  36. what happens to the poles on an electromagnet if the current changes direction?
    they switch