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Homework Help: Water level sensor

  1. Oct 7, 2006 #1
    i am having trouble with a problem about a capacitor based sensor.. i am to propose two seperate capacitance based sensors, one for soil moisture and another for water level..

    my problem is finding the time constant inorder to find C

    so i can use the equation C = k(e0)A/d to solve for k... as i would know C, A and d in my proposed system

    i know that C= T/R my R will be know except T which i can find... i know i can get T with a frequency meter device, but because i have little knowledge of what it is, i have no idea where i would place this device onto my capacitor circuit... (which is where my problem lies) how would i place a frequency meter into a simple RC circuit?

    im not sure if im on the right track, any help would be much appreciated
    Last edited: Oct 7, 2006
  2. jcsd
  3. Oct 8, 2006 #2


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    Science Advisor
    Homework Helper

    Your question isn't entirely clear.
    In order to use a frequency counter here, it would have to be capable of measuring an interval.
    Not a standard feature on frequency counters.

    Usually, C would be part of an oscillator circuit.
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