Iron filings align themselves in strong magnetic fields. This reveals the shape of the field patterns. A similar thing happens with the electric fields created by high voltage and by "static electricity." If small fibers are exposed to a very strong electric or magnetic field, they will align with the field and make it visible.
If your bottle has lables on both sides, peel the lable from one side of
the oil bottle. You can do this by picking at the paper lable with
fingernails while running warm water on it. An easier way is to soak one
side of the bottle in a shallow dish of rubbing alcohol for about 10 or 15
minutes. Peel off the gooey lable. Use a bit of alcohol and a paper
towel to clean off the remaining glue. (It really is easier to find a
bottle at the store that only has a lable on one side!)
Find the end of the roll, and unroll the steel wool part way.
We will use the scissors to make cuts ACROSS the wool. First trim the
wool
straight across to remove the frayed fibers, then repeatedly cut across
the wool to make many very narrow strips, narrower than 1/8 inch. Try to
cut them 1/16 inch if you can. This will give you thousands of short steel
fibers. Cut up about a heaping teaspoon of fibers, or about one square
inch of unrolled steel wool. Don't pack them down too much if you can
help it. If you use a really tiny bottle of baby oil, use less than a
teaspoon of fibers. If you use too large an amount of fibers, the fibers
will clump and settle to the bottom of the bottle too fast. If you use
too small an amount, the fibers will be hard to see.
If you have difficulty finding a magnet, try Radio Shack stores. They
sell small disk magnets which can be stacked up to form bar magnets. A
few dollars worth of their 1-inch "donut" disk magnets will be enough to
make several big stacks. These can be used in other future science
projects. You'll also wind up with a lifetime supply of refrigerator
magnets! Don't forget to keep magnets away from credit cards, computer
disks and video tapes, magnets can erase these. Keep them away from color
TV and computer screens, since they can create permanent color blotches
which can only be removed with a TV repair "degausser" coil or a cassette
tape bulk eraser.
(Hint: wave your magnets around an old Black&White TV screen, see what
happens to the picture!)
While the fibers are still mixed into the oil, hold a magnet near one
side of the bottle and watch the tiny fibers. They will all align
themselves and reveal the three-dimensional magnetic field pattern. It
helps to have the bottle in bright light so you can see the tiny fibers
against the white lable on the back of the clear bottle. The fibers
start to settle to the bottom in 10 or 15 seconds, so you'll have to
shake the bottle every so often if you want to keep experimenting.
______
|| ||
||____||
___----- -----___
/ | \
| _ \ |
| --__ \ |
| \ \ |
| - \ |
| __ ---___ | _______________
| __ | / MAGNET \
| ___-- --- | \________________/
| __-- / |
| _ / |
| / / |
| / |
| | | | THE FLOATING FIBERS MAKE THE MAGNETIC
| | | FIELD VISIBLE
\__________________/
BOTTLE
When the fibers settle out, shake them up again. If the fibers clump
against the magnet, then you are holding the magnet too close to the
bottle. Hold it about 1/2 inch or 1 inch away. Try holding the magnet
sideways as shown above. Also try it up and down. Also try holding
one magnet pole near each side of the bottle. Try an "N" pole with an
"N" pole (the poles which repel each other.) Also try an "N" pole
facing an "S" pole (the poles which attract.)
______
|| ||
||____||
___----- -----___
/ \
| |
| |
| |
| | / \
| | | |
| ? What will you | | |
| see? | | |
| | | |
| | | |
| | | |
| | | |
| | \__/
| | MAGNET
| |
| |
\__________________/
BOTTLE
______
|| ||
||____||
___----- -----___
/ \
| |
| |
| |
| |
S N | | N S
___________ | WHAT WILL | __________
/ \ | YOU SEE? | / \
\____________/ | | \___________/
MAGNET | | MAGNET
| |
| |
| |
| |
\__________________/
BOTTLE
You can improve your bottle by removing all lables and painting one side
of the bottle with white spray paint. This gives you a smooth white
background against which to view the floating dark fibers.
Follow the instructions above for making a magnetic field viewing
bottle, but instead of using steel wool, use hair! Straight black hair
works best. If you don't want to cut chunks out of your hairdo, you can
also use the artifical hair from a halloween mask, from an old doll, etc.
Use black hair so the fibers are easily seen. Gather a hank of hair, trim
the end straight across with scissors, then cut across the hair repeatedly
to create thousands of short fibers. Try to make them shorter than 1/8
inch. 1/16 inch fibers are best. Make about one teaspoon of hair fibers,
then dump them into a new bottle of baby oil and shake them up.
The E-Field viewing bottle works best with small charged objects like
balloons, combs, pieces of cloth attached to plastic rulers, etc. Try
combing your hair with a black plastic comb, then hold the comb near the
bottle and watch the fibers slowly line up with the spreading field
created by the comb. As usual, charging by contact (friction) only
works when the humidity in the room is low.
I've tried the bottle on VandeGraaff machines, but the field from these generators is so powerful that the fibers can become charged if the bottle is held too close. This causes the fibers to stick to the inside of the bottle. There's no way to get the fibers loose again, but if you wait several days they will become discharged and float free.