Connect one end of a wire loop to the battery and run the wire directly
over the compass. Touch the other end of the wire to the battery. Which
way does the compass point now? If you get some motion out of the
compass needle, this proves there is a magnetic field around the wire
when current is flowing. This relation between electricity and magnetism
is the thing that makes electric motors and generators work.
[Illustration: Figure 6]
Make Many From One
Lay the third needle (unmagnetized) on a table and stroke it with one of
the magnetized needles. (See diagram) Always stroke it in the same
direction. Raise the magnetized needle at least two inches on each
return stroke. Thus you can magnetize the needle by using the other
needle.
[Illustration: Figure 7]
Use the wire cutters to cut the first magnetized needle in short
lengths. (Cover the needle with a cloth to keep the pieces from flying.)
Can you show by using the compass that each piece is a complete magnet?
Hold one end, then the other, of each piece to a compass. Does each
piece have both a North Pole and a South Pole?
Magnetism and Animals
The things you have done show that electricity and magnetism are related
in many ways. Magnetism is mysterious, and there are still things to
discover about it. It is thought that animals and birds are aided in
their sense of direction by magnetism. It is commonly known that when a
person gets lost in the woods, he tends to go around in circles.
Possibly this is caused by the earth's magnetic field.
What Did You Learn?
1. Where are natural magnets obtained?
2. How can artificial magnets be made?
3. What material is needed for a permanent magnet? For a temporary
magnet?
4. How can you find out which is the North Pole of an unmarked magnet?
5. How many poles does a magnet have?
6. Which magnetic poles attract each other?
7. Why couldn't you make a compass out of a strip of plastic?
8. What causes the compass to change direction when a wire carrying
battery current is held over the needle?
9. List the materials you would need and tell how you would build a
homemade compass.
10. Tell what you enjoyed most about becoming acquainted with mysterious
magnetism.
LESSON NO. B-14
Credit Points 2
Give your appliances and lights a square meal
Would you say that having enough to eat was pretty important in the home
that you know?
The "food" for your appliances and lights is electricity, and like you
they must be "fed" enough.
What to Do
1. List the appliances and lights in your home.
2. See if any of them are "starving" for the electricity they need.
3. Learn how the electricity gets to where it's used.
4. Make a chart of the electrical circuits in your home.
5. Make sure that each circuit is protected with the right fuse or
circuit breaker.
Count Your Electrical Blessings
Many people in much of the rest of the world wish that they could trade
places with us, because we have so many electrical appliances in our
homes.
Public-domain text, read in full here on John Shaqi.
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