Motion of core 1, due to a change in the pressure ap p lied to a
diaphragm rig id ly attached to the core, is transm itted to coil 2.
The emf induced in th is coil for a given value of the magnetic
flux set up by electromagnet 3 is proportional to the velocity
of motion of the coil. To ob tain a curve of the pressure it is necessary
to am p lify the voltage over coil 2, integrate it and then
app ly it to the term inals of an oscillograph.
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