Electromagnets

By: Jacob

The topic of my investigation is electromagnets. An electromagnet is a magnet that has an iron core with wrappings of wire around it. Electromagnets are part of the modern day life. I chose this topic because my dad has worked for 27 years for BGE and he has gotten me interested in electricity.

There are many interesting questions about electromagnets. My specific question is "what would have the greater effect on an electromagnet, doubling the length of the nail or doubling the wrapping of the wire?" I thought of this question when I made an electromagnet for a school project. I wondered, what would effect an electromagnets magnetism more, increasing the wrappings or increasing the iron core?

The discovery of electromagnetism and its uses date back to more than 150 years ago! In 1820, Danish physics Professor Hans Christian Oersted discovered electromagnetism. He noticed that when he passed electric current through a wire, a nearby compass needle no longer pointed north. The first electromagnet was invented by William Sturgeon in 1823. William Sturgeon's model of an electromagnet was later improved by Joseph Henry in 1829. Michael Faraday, who was the son of an English blacksmith started as a bookbinder, but found the science books he was binding interesting. He took up physics and self-taught himself to a road of many discoveries. In 1821 he discovered that electricity could produce rotary motion. Electric motors today are based on his discoveries. He also discovered in 1831 that passing a magnet through a coil of wire produced an electric current. This idea gave birth to modem day generators. Today electromagnets are used in

monorails, door latches, door bells, vending machines, loudspeakers, microphones, metal detectors, car fuel gauges, voltmeters, and of course, motors, and generators.

There are many steps to making an electromagnet. First I gathered all of ray materials, which were nails, bolts, paper clips, wire, batteries, screws, tape, and jumpers. Next I made three electromagnets. The first electromagnet has 50 wrappings on a 3-inch nail and is used as my control. The second has double the wrappings (100 wrappings and a 3-inch nail). On the third magnet I doubled the nail length (50 wrappings and a 6-inch nail). I weighed the nails, paper clips, screws, and bolts on a gram scale. I tried picking up these objects with the electromagnets to determine their strength. Finally I recorded my results and calculated the weight. I used the same battery so my voltage was the same for all three magnets.

I discovered a lot of things about electromagnets and what effects their strength. I discovered that doubling the wrappings had the most effect. This magnet could pick up 65 grams. The double nail magnet could pick up much more than the control magnet at 42.6 grams compared to the control magnet which picked up 27.44 grams. After I was done testing the magnets the nails kept a little magnetism. I read that this is called residual magnetism.

Some things students could try next year with electromagnet KIC experiments are: They could try changing the size of the wire, use different battery voltages, or change the core material. A question I did not have time to test that could be used in a future KIC is "Does increasing the insulation effect the magnetic strength?"

Bibliography

Kindersley, Dorling. Science Encyclopedia. Dorling Kindersley Publishing. New York: 1994

Funk & Wagnalls. Microsoft Encarta 1994. 1994

O'Dwyer, John J. College Phvsics Wadsworth Publishing, Belmont, California. 1984