Name:______________________    Course: ________________________ Time:______________

Partner(s):_______________________________________________________________________

Purpose: To investigate air-column resosnance and determine the speed of sound in air.

Apparatus: resonance tube apparatus, audio signal generator, speaker, stand w/clamp, and water.

Theory: In wind instruments the wind (air) is made to resonate. Resonance makes the sound audible. In this investigation a small speaker, connected to an audio signal generator, will generate sound of required frequencies. The value of the frequency can be read from the front display. The speaker is held above the open end of the resonance tube which has water. The water level can be changed by lowering/raising the reservoir can.

As you lower the water level keep your ear next to the speaker and listen carefully. At the first resonance, L₁ the sound will be louder. If you keep on lowering you will hear the loud sound again at the second resonance, L₂. The wavelength, 8 is given by:

8 = 2 x (L₂ - L₁)

The speed of sound in air, V is given by:

V = 8 f , f = frequency.

Procedure:

1) Measure the room temperature using a temperature sensor, interface, and PC and calculate the speed of sound.

2) Make sure the resonance tube has the right amount of water to obtain all the possible lengths of air columns.

3) Mount the loudspeaker so that it faces into the open end of the resonance tube and is about 2 cm above it. Connect the loudspeaker to the signal generator and turn on the latter.

4) Set the frequency at 700 Hz and adjust the volume control to give a low but audible sound.

5) Determine the first resonance point by slowly lowering the water level. At resonance there will be an increase in the loudness of the sound.

6) At the resonance point, raise or lower the water level very slowly to determine the position for which the sound loudness level is maximum. Record the water level to the nearest millimeter in data table.

7) Lower the water level, determine the second resonance point, and repeat procedure 6.

8) Repeat procedures 4-7 for other frequencies and complete the data table.

________________________________________________________________________

DATA

Accepted value of the speed of sound in air (in m/s) at t ⁰c is given by

                    V = 331.4(1+ t/273)^0.5    or V = 331.4 Sq.Root (1 + t/273)

Measure the room temperature and calculate the speed of sound.

Room temperature (t) =

speed of sound (using temperature) = V = ____________

Average value of the speed of sound from resonance  = __________

                                                            % Difference = __________

Write a conclusion:

Goto www.prenhall.com/giancoli

Goto chapter 12, and select Physlet Problems. Do the first five problems. Write your answers below.