Magnet Tricks With Circle Magnets

Circular magnets attract other magnets and other forms of metal.

Magnetism is a fun way to get kids interested in scientific principles without memorization or textbooks. Several of the fundamentals concerning magnets can be taught through simple experiments that look like tricks. You can easily show that like forces repel and opposites attract, explain the poles of magnetism and show how the same magnet can attract or repel another, depending on which pole is facing the other. Magnets also attract different types of metals and alloys. Circular magnets are the most commonly used household magnet.

Metal Designs

Metal filings make for interesting designs when in proximity to magnets.

On a flat surface, place different sized circular magnets at various distances from each other. Place them far enough apart so that they are not attracting each other and lie flat and still. Over the magnets, place a sheet of paper so that it completely covers them. Dump metal filings in a pile across the paper and watch them scurry to the magnets, forming dark circular designs on the paper. Try it with a few filings and then try it with hundreds of filings. The strength and size of the magnets will determine how many filings cling to each.

You Are What You Eat

To fortify cereal with iron, companies can simply dust the recipe with tiny iron filings.

Not many people know this, but cereal is often fortified with iron by simply adding tiny iron filings to the cereal. Pour iron-fortified cereal into a bowl and add water, waiting until the cereal is mushy. Place a strong circular magnet into a plastic bag and seal it with no air. Swirl the bag in the cereal for a few minutes, then let it rest there another minute. When you pull the bag out, you'll see tiny pieces metal, no bigger than dust specks, clinging to the bag where the magnet is.

Seeing the Invisible

Compasses are affected by magnets and can show the shape of a magnetic field.

Magnetic fields are invisible, but it is easy to see them if you have the right tools. Place a circular magnet on a flat surface. Move a small compass into the magnet's range. The needle will point in a tangential direction to the magnet's force all the way around, showing where the field starts and ends.

Floating Fibers

To see a magnetic field in three dimensions, all you need is a stack of circular disc magnets, a clear plastic bottle, some steel wool and baby oil. Shred the steel wool into small metallic fibers. Fill the bottle with baby oil and dump in the fibers, sealing the bottle when done. Stack three to six circle magnets on top of one another and move the group toward the bottle. The fibers will rise toward the magnetic field in the oil, showing a three-dimensional field line and remaining suspended in the oil until you move the magnet away.

References

• NDT Resource Center: Circular Magnetic Fields
• Magnet Sales: Frequently Asked Questions
• Practical Physics: Experiments with Magnets
• Magnet Man: Cool Experiments with Magnets
• Eskimo: Seeing Magnetic Field Patterns in 3D