Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.
Measure the frequency of a plucked string
This project must be done by individuals or teams of 2.
We have examined in class the normal modes of oscillation
of a string stretched between two fixed posts,
placed under tension.
There are lots and lots of formulae which
predict the frequencies with which such strings
ought to oscillate;
they depend upon the tension and the linear mass
density of the string, and on the length of the string.
Your job is to set up a real string,
stretched under some known tension,
and verify that these predictions are correct.
If they aren't, you must explain the discrepancies.
Here are some tips:
- Hanging a known mass from one end of the string
is a good way to set the tension.
- One way to measure the frequency of a string
is to listen to it carefully,
and compare it to the frequency of some known
instrument: tuning forks, a piano, a guitar, etc.
- Another way to measure frequency is to record
a sound, digitize it, and then analyze the wave form
with software.
- Another way to measure the frequency is to
illuminate the string as it is vibrating
with a strobe light.
There are a number of applications for smartphones
which claim to produce bursts of light at set
frequencies;
if those don't work, you might ask the instructor
for a real strobe light.
Hand in sheets of paper, showing all your work.
Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.