Melde's Vibrating String (Elastic), 3B22.10

Location:

• Cabinet: [:WavesSoundCabinet: Waves & Sound] (WS)

• Bay: (A4)

• Shelf: #1

(attachment photo showing the fully set up demonstration)

Description:

The Pasco driver controlled by a function generator vibrates elastic cord. By varying the driving frequency and amplitude one can produce standing waves. The nodes and the antinodes can be seen better by using the strobe lights.

Setup:

1. Take the small ring stand with the elastic cord wrapped around it. Unwrap enough cord to stretch the cord a crossed the lecture bench.
2. With the Pasco vibrator, take the looped end of the cord and string in through the forked tip and onto the base set screw that is typically used to hold rods. This will anchor the cord.
3. place the lead brick in front of the vibrator to prevent the cord from pulling or tipping the the vibrator.
4. Place the strobe at each end of the cord in such a way that the strobe light are aimed at the cord and NOT at the students.

Cautions, Warnings, or Safety Concerns:

1. Strobes can bother students with epilepsy. This warning should be stated in class before doing the demonstration.

Demonstration:

Set the function generator so that the cord vibrates at it's fundamental frequency. This frequency depends on the tension of the cord and will differ every time this demonstration is set up. Do to the fact that we are using an elastic cord. Vary the driving frequency and amplitude to show the other mode of a standing waves bond at both ends. Point out the nodes and the antinodes. Use the strobe lights to make the vibrating cord stand still or make it roll in slow motion.

References:

1. List any references

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