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<p>A. Accelerometers
<p>An accelerometer is a linear seismic transducer which produces an electric
charge proportional to the applied acceleration. A simple model of an
<br>accelerometer is shown in \Fig{accelerometer1}(a). A mass is supported
on a piece of piezoelectric ceramic crystal which is fastened to the frame
of
<br>the transducer body. Piezoelectric materials have the property that
if they are compressed or sheared, they produce an electric potential between
<br>their extremities, and this electric potential is proportional to the
amount of compression or shear. As the frame experiences an upward acceleration
<br>it also experiences a displacement. Because the mass is attached to
the frame through the spring-like piezoelectric element, the resulting
<br>displacement it experiences is of different phase and amplitude than
the displacement of the frame. This relative displacement between the frame
<br>and mass causes the piezoelectric crystal to be compressed, giving
off a voltage proportional to the acceleration of the frame.
<p><img SRC="cid:part1.3C4A3406.F0BD114D@grieg.uib.no" height=142 width=362>
<p>--
<br>Richard Brekne
<br>RPT, N.P.T.F.
<br>Bergen, Norway
<br><A HREF="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A>
<br><A HREF="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broadpark.no/~rbrekne/ricmain.html</A>
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