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2009

# Making Speakers

Bonnie Lasby Physical and Engineering Science Dean’s Office University of Guelph
blasby@uoguelph.ca

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
martin@physics.uoguelph.ca

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
omeara@physics.uoguelph.ca

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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