PASCO TD-8565, Instruction Manual And Experiment Manual

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012-05110C Adiabatic Gas Law Apparatus
7
Apple II compatible computers
➤ NOTE : Operation with the Apple II series of
computers is severely limited by the speed of the
computer. If there is any other computer you can
use rather than an Apple II, please do so.
➀ Connection and calibration procedures are as
described for the IBM. We do not recommend cali-
brating the apparatus in SI units, since the round-
off error introduced by the Apple will be greater
than the volume of the cylinder in m
3
.
➁ Because of the input limitations of the Apple II, it
is not possible to graph all three traces in oscillo-
scope mode. Instead, choose "C" for fast data col-
lection.
Enter the delay between data points as 1.0 ms, and
collect about 100 data points. (Actual delay be-
tween readings on individual channels will be 3.0
ms, since the computer alternates channels for each
reading.) Press the space bar when you are ready,
and
simultaneously
change the volume. The input
is
not
automatically triggered.
③ Once the data is obtained, return to the main menu
and choose “P” to plot the data. The best graphs are
obtained when the inputs are uncalibrated; other-
wise the difference in scales between data sets may
result in only one of the lines being visible.
Expansion of a Gas
To perform a qualitative demonstration of the adiabatic
expansion of a gas, do the following:
Clamp the front foot of the apparatus base to the table.
Fill the cylinder to maximum displacement at atmo-
spheric pressure. Close the gas cock and compress the
gas. Set the trigger level to a value slightly higher than
the steady value and set the slope to positive or "going
up". When ready to take data, compress the gas to this
initial volume, hold it there until equilibrium is
achieved (about 30 seconds), press "S" for Single
Sweep, and then very rapidly expand the gas fully.
When compressing the gas, some work is done against
friction in the cylinder, but the part of the cylinder that
becomes warm is not in contact with the gas. How-
ever, when expanding the gas, the part of the cylinder
that is warmed is in contact with the gas. For this
reason, the expansion data does not give good quanti-
tative results.
Figure: Graph of Voltage vs. time (Apple II version)