3E20.15 - Loudspeaker Resonance

Hook the wave generator, 50 ohm resistor, and 4 inch speaker in series.  Set the oscilloscope on the X-Y plot.  Measure across the resistor with channel 1 and across the speaker with channel 2.  NOTE: Only one of the ground wires on the oscilloscope leads needs to be connected. As you sweep the frequencies, you will see the plot on the oscilloscope increase to a maximum when you reach the resonant frequency of the speaker.
You will also be able to hear this by listening to the amplitude of the speaker change as you sweep the frequencies.
Code Number:
3E20.15
Demo Title:
Loudspeaker Resonance
Condition:
Excellent
Principle:
Speaker Construction and Sound Reproduction.
Area of Study:
Acoustics
Equipment:
4 inch speaker, 50 ohm resistor, oscilloscope, wave generator.
Procedure:

Hook the wave generator, 50 ohm resistor, and 4 inch speaker in series.  Set the oscilloscope on the X-Y plot.  Measure across the resistor with channel 1 and across the speaker with channel 2. 

NOTE: Only one of the ground wires on the oscilloscope leads needs to be connected.

As you sweep the frequencies, you will see the plot on the oscilloscope increase to a maximum when you reach the resonant frequency of the speaker.  You will also be able to hear this by listening to the amplitude of the speaker change as you sweep the frequencies.     

References:
  • B. T. G. Tan, "Fundamental Resonant Frequency of a Loudspeaker", AJP, Vol. 50, # 4, p. 348, April, 1982.   

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