Physics 111 Lab #9:
Resonance and Transverse Waves
Key Activities:
Resonance
By attaching a spring and hanging mass at the end of a string that is tugged at an adjustable "driving" frequency by a mechanical vibrator, resonant behavior of the mass and spring can be studied. The figure in the lower right corner shows the resulting resonant behavior, namely a dramatic increase in the vibrational amplitude of the hanging mass, when the mass is driven at its natural frequency, fo = 1.8 Hz (see below). The Q value of this oscillator, which reflects the sharpness of the resonance, is estimated to be roughly 23.
Standing Waves on a String
Standing waves will be studied on a string tied between a mechanical
vibrator and a hanging mass. By using a signal generator to "drive" the
mechanical vibrator, the amplitude and frequency of waves in the string
can be varied, while the tension in the string can be controlled using
the hanging mass (Lectures
26,
27,
28).
Expected resonant mode patterns of the
string, corresponding to resonant frequencies fn =
(n/2L)(T/µ)0.5, where n (= 1,2,3,...) is the mode number,
L is the length of the string, T is the tension in the string, and µ
is the mass per unit length of the string (Lectures
26,
27,
28).
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