Mega-Magnet

Introduction

Congratulations! You are the proud owner of one very powerful magnet! These “Mega-Magnets” are salvaged from computer parts, and so they may have a chip or two and a scuffed-up paint job, but they are just about as strong for their size as magnets get, and certainly a good buy for the money! Following are just a few possible applications for your Mega-Magnet.

Safety Precautions

The materials in this lab are considered nonhazardous. Keep magnet away from computers and computer screens and other electronics. Use care when handling strong magnets. The magnet can quickly snap to any magnetic object, resulting in pinched fingers or cracked magnets. Wash hand thoroughly with soap and water before leaving the classroom or laboratory. Please follow all laboratory safety guidelines.

Procedure

Demonstrating the Iron Content in Breakfast Cereals

Fill a petri dish with water, adding more water than the dish can hold, so that the water surface is domed slightly above the rim of the dish. Place a few flakes of cereal in and show how they are attracted to the magnet (you must hold it rather close). This works well as a demonstration for the overhead projector.

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Alternative Procedure for Demonstrating the Iron Content in Breakfast Cereals

To actually show the iron in the cereal, place one cup cereal and one cup water in a blender and blend until smooth. Pour the slurry into a plastic cup and, while holding a corner of the magnet to the side of the cup, stir the slurry slowly with a white plastic spoon. A dark spot will soon appear where the iron filings from the cereal congregate on the inside of the cup. The back of the spoon may be held behind the spot to make it more visible. (If the blender walls are not too thick, you may be able to forego the cup and just hold the magnet alongside the blender as it blends!)
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Demonstrating the Paramagnetic Nature of Gases

Again, using an over-filled petri dish, blow a small (1–2 cm diameter) bubble of O2 gas in the center and show how it is attracted to the magnet. Compare it to a N2 or CH4 bubble which should show no paramagnetism.
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Demonstrating the Paramagnetic Nature of Solid and Liquid Substances

Place the magnet on a centigram balance, zero the scale and then hold a paramagnetic substance over the magnet (in very close proximity, but not touching). The scale should show a negative reading as the magnet is lifted slightly upward proportional to the degree of paramagnetism.
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Demonstrating Eddy Currents

Drop the magnet through a large copper or aluminum pipe and observe from above how it slowly drifts down as electrical fields generated in the pipe by the changing magnetic field act to oppose the magnet’s descent. (Have something at the bottom to assure a soft landing for your magnet.) If a pipe cannot be purchased that is large enough, you may want to break off a chip of the magnet and use it.
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Demonstrating the Magnetic Ink Used in Printing Money

Hold a dollar bill dangling loosely in one hand and approach it from the side with the magnet. You should see a definite deflection of the bill toward the magnet (unless it’s a counterfeit bill!) Alternatively, just tear off a little corner and show how the magnet can pick it up.
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Maneuvering Objects by Remote Control

Example—To initiate a reaction in a closed container. Cut the bottom off a plastic pipet and use it as a test tube to hold one reactant (solid or liquid). Place the other reactant in an Erlenmeyer flask. Slip a paper clip down one side of this test tube, then moving the magnet down the outside of the flask, carefully lower the test tube down the inside wall. Stopper the flask with a one-holed stopper (connected to your gas collecting setup). Then, when everything is in place, turn the magnet to pour out the test tube’s contents inside the flask!
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Magnetic Art!

Tape this magnet to the bottom side of a thick piece of corrugated cardboard. Then turn it and use a variety of iron objects (e.g., nuts and bolts, paper clips, washers) to create magnetic sculptures that appear to defy gravity!
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Herculean Refrigerator Magnets

No more wimpy magnets letting all your refrigerator graffiti fall off each time you open the door. This magnet will hold several times its weight securely in place! For instance: how about four legal pads stacked on top of each other! Or slip one inside a box of cereal, between the cardboard box and the plastic lining, and use it to hold the entire box to the refrigerator. (Discover the shelfspace you never knew you had!).
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References

Special thanks to Bob Becker, Kirkwood High School, Kirkwood, MO, for providing us with these activities.

Next Generation Science Standards and NGSS are registered trademarks of Achieve. Neither Achieve nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of this product, and do not endorse it.