Making a Magnet that Turns On and Off!

(Electro)Magnetism

Have you ever wondered how magnets work? The explanation of this phenomenon eluded scientists for a very long time, and was not solved until the mid-19th century.  Today, we learned about the relationship between electricity and magnetism and found that moving electric charges create a magnetic field, or space where the effects can be felt by other ferromagnetic materials.

After discussing magnets, how magnetic fields are created and an electromagnet’s cores and coils, students built their own electromagnets of varying strengths to pick up paperclips. Students worked in groups to make electromagnets using a battery, a resistor, a wire, and a nail.  Students investigated how the number of wire coils around the nail affected the strength of their electromagnet.  We learned that the more times you coil the wire around the nail, the stronger the magnet became – your student should be able to tell you why this is. (Hint: It has to do with the relationship between electricity and magnetism!)

We finished the lesson by talking about the uses of electromagnets and seeing a demonstration of another interesting property of some materials, called diamagnetism.

Additional Information:

Try this at home!  If you have a sewing needle and a relatively strong magnet, try to align the crystal domains (mini-magnets) of the sewing needle by stroking it with the magnet repeatedly in one direction. Then see if the needle exhibits any magnetic behavior (repelling or attracting other magnetic materials objects.)  http://www.scientificamerican.com/article/find-magnetic-north-with-compass-bring-science-home/

Author

Dr. Catherine Sukow

Dr. Sukow's interest in science education began when she was a teenager, with an extended visit to San Francisco's Exploratorium. In college, she had summer jobs in a similar, smaller, museum. She focused her Master's research at NCSU on the structure of metal silicides on silicon, and her Ph. D. work at Brandeis on the structure of crossbridged actin bundles. While volunteering in her childrens' schools, she was reminded how much fun it is to teach science, and is happy to be teaching now with Science from Scientists. In her spare time, she also enjoys yoga, choral and solo singing, and attempting a variety of international cuisines.

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