The task of this experiment is to measure the
dispersion relation w=w(k) for a linear chain. It
serves as a preparation for the Debye specific heat experiment.
setup to register the amplitude
of a selected mass as a function of time.
the linear chain with N=13 to oscillations.
the elongation u(t) as a function of time with Scientific Work Shop.
the Fourier transform of u(t).
the excitation frequency (and the position) until you have all frequencies
of the system.
the resonance frequencies according to magnitude and plot them as a
function of n/N=qa/p.
(If there is a jump in the plot
reassign the numbering).
the experiment with N=9.
the nodes for the different resonance frequencies.
them in the plot frequency versus n/N and draw a characteristic standing
a theoretical curve to the experimental points.
the effective ratio of spring constant divided by mass
the mass of the pendulum
the spring constant by attaching a mass of about .5 kg and measuring the
the ratios k/m (m=mass of pendulum in linear chain) between the fit of the
dispersion relation and the individual measurements
Using Scientific Work Shop (SWS)
starting the computer the SWS-box should be turned on
photo-diode with input A and (on PC) drag analog plug to A.
graph to A
sampling option, use 20Hz for Linear Chain frequencies less then 5Hz and
50 Hz for larger ones
optimal range on graph by double-click left scale
stop and restart Monitor click Stop twice (one time to change
For fast Fourier transform (FFT)
FFT to A
on the right side of FFT to choose the number of sampling points: 1024
frequency axis selects automatically twice the value for the sampling