Basic Electricity

PDF Version
  • Question 1

    A permanent magnet is a device that retains a magnetic field without need for a power source. Though many of us have experienced the effects of magnetism from a permanent magnet, very few people can describe what causes permanent magnetism. Explain the cause of permanent magnetism, in your own words.

    Reveal answer
  • Question 2

    If we were to trace the magnetic lines of flux extending from this bar magnet, what would they appear like?

    Reveal answer
  • Question 3

    Magnetic poles are designated by two labels: “North” and “South”. How are these labels defined? Explain how we can experimentally determine which ends of a magnet are “North” and “South”, respectively?

    Reveal answer
  • Question 4

    Devise a method of identifying the poles of a magnet that is too large and heavy to move.

    Reveal answer
  • Question 5

    What happens to the magnetic lines of flux emanating from a magnet, when an unmagnetized piece of iron is placed near it?

    Reveal answer
  • Question 6

    Describe the so-called “domain theory” of magnetism, as it applies to permanent magnets.

    Reveal answer
  • Question 7

    Define the following terms:

    • Ferromagnetic
    • Paramagnetic
    • Diamagnetic
    Reveal answer
  • Question 8

    A mechanic visits you one day, carrying a large wrench. She says the wrench became magnetized after setting it near a large magnet. Now the wrench has become an annoyance, attracting all the other tools in her toolbox toward it. Can you think of a way to demagnetize the wrench for her?

    Reveal answer
  • Question 9

    Suppose we needed to shield a sensitive electronic instrument from external magnetic fields. How would you suggest we do such a thing? How can we keep stray magnetic fields away from this instrument?

    Reveal answer
  • Question 10

    Find a magnet and bring it with you to class for discussion. Identify as much information as you can about your magnet prior to discussion:

    • Location of poles
    • Which pole is North, and which pole is South
    • Type (metal, ceramic, etc.)

    Please be careful to keep any magnets away from cassette tapes, computer disks, credit cards (with magnetic information strips) or any other form of magnetic media!

    Reveal answer