# Homework Help: Standing waves.

1. Mar 28, 2005

### lektor

This is not homework question but more of a personal interest question.

Can anyone help explain why it is that in the fundamental of a string the 2 impulses superimpose to form:

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• ###### standing wave.jpg
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2. Mar 29, 2005

### Andrew Mason

The position of the fixed ends of the string determines the wavelength. The fundamental is the longest wavelength of vibration for which the distance between fixed ends is the distance between two adjacent nodes. Any longer wavelength would require the fixed end of the string to move. The distance between two adjacent nodes is 1/2 a wavelength.

AM

3. Mar 29, 2005

### Ouabache

With a string, what is the standing wave, standing between?

With electrical signals, standing waves occur within a channel (wire, optical fiber etc.). The signal actually propagates the length of the channel and then radiates back. Maximum signal is transmitted when the forward/reflected ratio is 1:1

Thinking about the standing wave graph (time vs amplitude) that lektor gave, does the acoustic wave propagate out to a boundary and reflect back again to its origin? Where would be the physical position of the origin and boundary?