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Re: IONS

At 17:38 9/20/98 +0100, you wrote:
... A capacitor with pure
water between its plates would have 81 larger value of
C than an air capacitor (for the same geometry). I never
heard about water capacitors. Do they exist?
.... Ludwik Kowalski


Sadly they do. Let me explain.
A popular method of implementing a fuel level transmitter on board heavy
iron aircraft is with a capacitance sensor-whose electrodes control the
repetition rate of an oscillator.

The dielectric constant/permittivity of fuel liquids is higher than air,
so that full tanks represent higher capacitance.

However, water has much higher dielectric constant than fuel, so a tank
that gains moisture can read high - not desirable.

Brian Whatcott
brian whatcott <inet@intellisys.net>
Altus OK