WM4.1 Air Columns
Same concept as the organ pipe below. Ungraduated cylinders are filled with water. With a damp finger, lightly rub the top of the cylinders. The more water, the higher the pitch.
Measurement of beat frequencies. Attach the speakers to audio oscillators operating at different frequencies.
WM4.3 Organ Pipe of Variable Length
The length of the air column determines the pitch of the organ pipe. Attach the organ pipe to the air supply on the lecture table.
WM4.5 Tuning Forks
Using two different types of forks (ie. different frequencies), the class could hear the beat frequencies. Using the same frequency forks, strike one and place it near the other. The second one will begin to vibrate. Then stop the first by placing your hand on it, and the class hears the second.