Although magnetic fields are invisible, you can "see" them. Gather magnets of various shapes, one white paper plate for each magnet, iron filings, adhesive tape, safety goggles, a disposable face mask, rubber or heavy latex gloves and spray adhesive. Ask an adult to help you. Center and tape a magnet on the bottom side of a paper plate. Perform the remainder of this project outside. Put on the goggles, face mask and gloves. Shake iron filings gently onto the top side of the paper plate and watch the magnetic field take shape. Carefully spray the surface of the plate with adhesive to maintain the pattern, holding the spray can far enough away so the force of the spray does not disturb the iron filings. Never breathe the spray adhesive fumes or get the adhesive in your eyes. Try this project with two bar magnets, first placing the opposite poles together and then the same poles together. Compare the pattern of the magnetic fields.
Try your hand at creating a 3-D display of a magnetic field using clear, unflavored gelatin, iron filings, a clear jelly jar, a magnet and adhesive tape. Ask an adult to help you. Make the gelatin according to the directions on the package. Mix in the iron filings and pour the mixture into the jelly jar. Allow the gelatin to cool and thicken but not set. Tape a magnet to the outside bottom of the jar and shake the gelatin. Place the jar in the refrigerator until the gelatin sets. This project may take several tries but eventually you will see a 3-D magnetic field. Try using other shapes of magnets.
Experiment with erasing magnetic tape memory. Find an old videotape you don't want anymore, a VCR/TV hookup, a rare-earth magnet (neodymium-iron-boron) and pencil. Play the videotape for about 15 seconds. Eject it from the VCR and hold open the flip cover of the videotape. Hold the magnet over the exposed videotape, and move the magnet back and forth. The videotape will be attracted to the magnet. Put the videotape back into the VCR and rewind it slightly. A portion of the video will be missing. Videotapes, cassette tapes and old floppy discs use ferric oxide (iron oxide) particles to record information. The magnetic field of the magnet realigned these particles, erasing the information on a section of the videotape. In your display, caution individuals not to use magnets, or objects containing magnets, near computer disks or credit cards.
Amaze everyone who sees your science fair project by "magically" attracting a dollar bill with a magnet. Collect materials with various attraction levels to magnets (such as an iron bar, old copper penny, steel nails, paper and cotton fabric), a rare-earth magnet and dollar bill. Fold the dollar bill width-wise at about 55 percent of its length. Challenge the fairgoers to pick which of the items you have provided will be attracted to the magnetic field of the rare-earth magnet. When they have finished, ask them if they are certain they have chosen all the magnetically attracted items. Hold the magnet close to the dollar bill. The ink used on U. S. paper currency contains a small bit of iron, and the dollar will be attracted to the magnet.