School of Physics Lecture Demonstration Manual

Wb-3 The Gas Tube

Published: Tuesday 14 March 2006 - Updated: Wednesday 30 March 2011

Aim

To demonstrate standing wave patterns in a pipe using sound waves and gas jets to indicate the pressure profile.

Apparatus

Diagrams

Click on pictures to enlarge.

Gas Tube

Videos

The Gas Tube

Description

A metre long pipe has a series of small holes drilled equidistant along its length and is connected to a natural gas supply. At the other end a horn loudspeaker is driven by the Minilab signal generator and power amplifier combination. The gas supply is adjusted to give a flame height of approximately 2 inches.As the frequency is varied , standing waves are produced, pressure maxima and minima are formed in the pipe, as indicated by the height of the flames.

The following frequencies produced the indicated modes.

 

frequency (Hz)

Mode (Number of wavelengths)

200

1/4

400

1/2

800

1

1600

2

 

Safety notes

Electrical safety 

Fire/Burn safety 

Maintenance 

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