Applied Science - Technology (4B) Lab
 OBJECTIVES: Designing an electromagnet. Discovering the power of electromagnets. VOCABULARY: electricity electromagnet electromagnetism magnet magnetic field MATERIALS: battery holder (1 per group) D batteries (2 for each battery holder) alligator clips (2 per group) 20 gauge wire (enough to make coils) large nail (steel) Students make an electromagnet.
 BACKGROUND: An electromagnet is a magnet that employs electric currents to generate its magnetic field. In 1825, W. Sturgeon described an electromagnet that allowed a 7 oz. iron bar to pick up a 9 pound iron mass. When the electrical connection was broken, the weight immediately fell. In 1829, H.C. Oersted discovered that an electric current could turn a magnetized needle. Also in that year, D.F.J. Arago and Sir Humphry Davy picked up iron filings by an electrified wire on steel needles. This however, was not an electromagnet. Electromagnets are temporary magnets that can be turned on and off just by removing one of the connections to a battery. They can be made very strong by wrapping more coils around the electromagnet. They are found in doorbells, door chimes, telephone receivers, telegraphs, relays, loudspeakers, electric clocks, fans, refrigerators, washing machines, generators, circuit breakers, and many other electrical items. PROCEDURE: This experiment shows students that a more powerful magnet can be made by increasing the number of coils around the bar while still using the same energy source (in this case a total of 3 volts).    Follow the directions on the worksheet. Electromagnets can concentrate "energy" to make a powerful magnet. These electromagnets are temporary. You may want to extend this lab by joining two battery packs (a total of 6 volts). The electromagnet will also get stronger. The number of coils and the original voltage can create different electromagnet strengths.    Make sure the insulation on the ends of the wires is scraped off. The answers to the lab sheet are dependant on how the students do the activity. Make sure the coils on the electromagnet are wound tightly. The wire must have contact with the nail.    ANSWERS:    NOTE: When the students make an electromagnet in this fashion, the wire will become very warm. 1.  The number of paperclips will depend on how tight the coils are and the type of paperclips.  2.  The paperclips fall.  3.  More than in number 1. 4.  No. 5.  More than 3. 6.  There should be a little magnetism left.  7.  Maybe 1 for a short period of time.       CONCLUSIONS: The force is stronger.