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Making Speakers

Bonnie Lasby Physical and Engineering Science Dean’s Office University of Guelph

I prefer to do this as an activity as opposed to a demonstration, and have found that it works very well for students in Grades 7 to 12 visiting the University. I start with a discussion about sound and then compare a speaker to the human ear. In the discussion on speakers, I also talk about magnets and how they work, and I explain the difference between permanent magnets and electromagnets. After this discussion, I explain how to make speakers using a plastic cup, a magnet, and a coil of wire. Each student makes his/her own speaker and then tests it. Read More...

An Inexpensive Magnetometer

Dave Doucette (OAPT President) Richmond Hill High School, Richmond Hill, Ontario

Several years ago I was in need of a cheap, easily assembled, sensitive magnetometer. The intent was to design a tool for students to palpably observe the magnetic field around a current carrying conductor. Deflection of a compass needle lacked the ‘wow factor’ I sought. The solution turned out to be beautiful in its simplicity. Read More...

Bernoulli’s Principle

Martin Williams, Department of Physics, University of Guelph

In this demonstration, we utilize simple everyday household items to test Bernoulli’s principle and verify the apparent counterintuitive nature of its predictions. Read More...

Wire Fire!

Joanne O’Meara, Department of Physics, University of Guelph

This demonstration is a nice way to illustrate the P = I 2R relationship that is discussed in electric circuits. Figure 1 illustrates the equipment: a Variac transformer takes the wall output of 120 V and generates a variable voltage from 0 to 140 V. This is then sent through a Hammond Manufacturing transformer (167X5), converting down to 5 V output. We use this second transformer in order to increase the current through the wires. The output from the second transformer is connected to three wires in series: approximately 10 cm in length of each of ~18 gauge Nichrome, steel and copper. A piece of folded paper is placed on each wire. Read More...
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