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Archive for the ‘Physics’ Category

Experiment 10: Standing Waves and the Speed of Sound in Air

Experiment 10: Standing Waves and the Speed of Sound in Air


Object: To measure the speed of sound waves propagating in air using a resonance tube and compare the measured speed with the predicted value given by treating the air as an ideal gas.


Introduction: When a surface [ like the end of a tuning fork, or the speaker(s) in your smartphone, or your vocal cords] is vibrating , the air around it is set into vibration producing a sound wave . If the air is constrained to vibrate in a long narrow region, for example the air in a tube, Fig. 1, we have a one-dimensional wave. If we limit our analysis to sinusoidal vibrations (Harmonic Oscillator!!) then the displacement from equilibrium position, s1, at time t for the air particles having position x can be given by:

            s1  = A sin (kx    t)                ( 1 )

where  A  represents the