Consists of a pair of speakers hooked up to the amplifier and a function generator.

NOTE: Last time we tried this demo, we failed to get consistently noticeable results. Needs testing in the lecture hall.

To demonstrate the interference pattern produced by two sound sources.

• A pair of speakers
• Function generator
• Amplifier

1. Place the speakers on a cart at least two feet apart. You will have to adjust this distance according to your frequency.
2. Attach the function generator output to the Amplifier and connect the amplified outputs from the amplifier to the input at the back of the stereo labeled “Phono Right”.
3. Ensure the stereo is set to play the phono input
4. Attach the two cables from the back of the stereo to the speakers as shown in the picture below
5. Test the speakers to check if the polarity is right (they only work one way)
6. Select a frequency on the function generator and turn up the volume on the stereo
7. A frequency of about 1000 or 2000 Hz gives noticeable pattern although superimposed on the interference pattern are the nodes and antinodes from standing waves produced by reflection in the lecture theater.
8. The table (or cart) can be turned so that any interference pattern produced in the direction of the speakers can be swept across the audience producing audible maxima and minima.