Determination of the Speed of Sound Using a Resonance Tube

Objective

To determine the speed of sound in air using a resonance tube.

To study the relationship between the air-column length L and the tuning fork frequency f.

To obtain the speed of sound from the graph using the slope of the best-fit line.

Theory

In a closed–open resonance tube, the first resonance (loudest sound) occurs when: L= λ​/4

The wave equation is: v=fλ

Substituting λ=4f L=v/4f

This can be written in the straight-line form: L= v/4 *1/f

Compare with: y=mxy = m xy=mx

Thus:

y≡ L (vertical axis)

X= 1/f (horizontal axis)

m=v/4

Apparatus

1- Resonance tube with adjustable water level.

2-Set of tuning forks with different frequencies

3-Rubber hammer.

4-Meter ruler (cm scale).

Procedure

1-Fill the resonance tube so that the air column is initially short.

2-Select a tuning fork with a known frequency f.

3-Strike the tuning fork gently and hold it near the open end of the tube.

4-Slowly raise or lower the water level until the loudest sound is heard (first resonance).

5- Measure the air-column length L from the water surface to the open end of the tube.

6- Repeat with tuning forks of different frequencies.

7- Convert all lengths from cm to m and calculate 1/f for each reading.