Science projects

PROJECT
MAKING A PRINT OF A MAGNET'S
MAGNETIC LINES OF FORCE

INTRODUCTION:

A magnet is attracted to iron, and either is attracted to or repelled by other magnets. The magnetic force around a magnet is a series of areas of attraction, with non-attractive areas between them. This is much like a sound wave, which is a series of areas of condensation and rerafaction.

We can see these "lines of force" by using iron filings, and with the help of special paper, make a print of them.

MATERIALS NEEDED:

Several small magnets of different shapes
*A stationary box top or bottom
Masking tape or equivalent
Iron filings
**Diazo print paper 8 ¹/₂" x 11"
Spotlight that can be hand held
Household ammonia or stronger ammonium hydroxide
3 pound coffee can with lid
Baby food jar or equivalent
Colored construction paper (optional)
Glue (optional)

*Any thin but sturdy box will work. It needs sides that are long enough to hold the magnet taped beneath it above the table.
**Diazo print paper can be obtained from a blueprint type print shop. It is light sensitive and develops with ammonia. You can use it in normal room light, but keep it emulsion side down when not being worked with, and the extra in its light proof package. Be sure to keep it away from ammonia fumes. It comes in black or blue image colors.

PROCEDURE:

Making the print

1. Choose a small magnet and tape it to the center of the underside of the box lid, so that the sides of the lid hold the magnet off the table.

2. Take a sheet of diazo paper from its light tight package, BEING CAREFUL NOT TO TOUCH THE YELLOW EMULSION SO FINGERPRINTS WILL NOT SHOW. Use as little room light as is practical to protect the emulsion, but it is slow to be exposed, so don't worry. Cut the sheet into two 8 & 1/2 x 5 & 1/2 pieces, and return one to the package so it will not be damaged by room light.

3. Tape the diazo paper, yellow emulsion side up, on the top of the box lid.

4. Very carefully, dust the paper with the iron filings. now gently tap the top of the box lid and watch the iron filings move to form the lines of force. Continue taping until you get the image you want. If you mess-up, just remove the paper, pour the iron filings back, and start over.

5. When you have the image you want, turn the spot light on and hold it above the paper, shining down on it, to expose your print. Wave the spotlight around to expose the paper evenly. You will see the yellow emulsion turn white. When it is all white, turn the spotlight off.

6. Now simply un-tape the paper and pour the iron filings back into the container. You are now ready to develop your print. Keep the print out of the room light until you are ready to develop it

Developing the print

7. Fill the baby food jar about 3/4 full of the household ammonia and place it in the center of the coffee can. Keep the lid on the coffee can so the fumes won't escape.

8. Now you are ready to develop the print. Place your print to be developed along the inside of the coffee can with the emulsion side toward the baby food jar. Close the coffee can with the lid and wait several minutes for the fumes to develop the print.

Don't be in a hurry now. You want it to completely develop. If you develop more than one print at a time, it will take longer because the fumes will have to penetrate one print to reach the next. You can speed up the development by heating a nail on a hotplate, and then with tongs, drop it in the baby food jar of ammonia. This will increase the amount of ammonia fumes released.

PREPARING YOUR PRINTS FOR DISPLAY:

9. Trim your print to better fit the size of the image.

10. Glue the print to a piece of colored construction paper that is larger than the print, and trim the construction paper to leave a colored border around your print.

11. Use a spot of glue in the center of the print to glue the magnet, in the same position it was when you made the print, on the magnetic lines of force. This really makes the print interesting because you can more easily compare prints from different shaped magnets. If you want, you can use colored construction paper and cut out a representative shape of the magnet to glue on the print instead.

OTHER THINGS TO TRY:

Do prints of different shaped magnets so you can see how the shape of the magnet affects the shape of the magnetic lines of force.

Use 2 identical magnets. Face them so they attract each-other and then tape them to the bottom of the box top with a space between them. Now when you make a print, it will show the magnetic lines of force attracting the two magnets to each-other.

Do the same as above, but with the magnets repelling each-other. This makes a really cool print. You will be glad you did this one.

Try a magnet, with an iron nail taped a short distance from it.

FURTHER STUDY:

Don't stop here! It't time to make a trip to the library to learn more about magnets. These prints, with a good report, would make a nice science fair entry.

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