= Driven string standing wave experiment
The University of California, Santa Barbara's cord demonstration uses a <function generator> and mechanical driver loosely attached near a clamped cord end. The other end passes over a pulley to a mass hanger, setting <tension>. Its photograph shows operation with a strobe; the page reports measured and calculated lowest-mode <frequencies>. Varying drive <frequency> at fixed loading selects higher <normal modes>. This clamp arrangement differs from a string tied directly to a moving driver.<40.75 -- Standing waves on cord (UCSB Department of Physics)>[Standing waves on cord, opening apparatus description, operating photograph, fixed-end explanation, and calculated versus measured frequency table]{ref}
A controlled <frequency> scan holds the cord, endpoint separation and hanging load fixed, then varies <frequency> slowly to locate large steady <amplitudes>. Read stationary <nodes of a standing wave> and count loops; compare the inferred $\lambda=2L/n$ with $c=f\lambda$. As additional checks, compare small drive settings, repeat the scan in reverse, and change only the hanging load to test the predicted square-root <tension> dependence. These checks test the ideal model rather than adding measurements to the demonstration.
An elastic cord's stretched <linear mass density> can differ from its relaxed value; the published calculation uses the relaxed value. A strobe can freeze motion at misleading settings, so identify <nodes of a standing wave> across several snapshots. A moving attachment need not be an exact <node of a standing wave>. These limits qualify any comparison with ideal fixed-end <eigenfrequencies>.<40.75 -- Standing waves on cord (UCSB Department of Physics)>[Standing waves on cord, clamp and nearby driver distinction, optional strobe, and relaxed-cord linear-density assumption]{ref}
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