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Homework Help: Frequency cutoff/lab

  1. May 26, 2015 #1
    Hello there.I have a question about how to find the frequency cutoff in a breadboard with oscilloscope,multimeter etc
    Ok the circuit it simple.Ac voltage source in series with a resistor,which is in series with a capacitor.I am given that in the frequence cutoff the voltage of the capacitor is lets say T.
    So how to find the cutoff frequency?Here is how i think i should find it.

    I connect the function generator to the resistor and capacitor.Now i place the multimeter(measuring voltage) across the capacitor.
    I change the frequency,until i see that the multimeter got the known voltage(aka T).Then i connect the multimeter across the capacitor again and i measure the frequency.Then i found the frequency cutoff.

    Is this the way it should be done?I thought to use the oscilloscope for the cutoff but i don't think i can do it that way.

    Thanks in advance for your time and attention
    Last edited by a moderator: May 26, 2015
  2. jcsd
  3. May 26, 2015 #2

    rude man

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    Homework Helper
    Gold Member

    You should use the oscilloscope for everything.
    Start with a low frequency, measure peak-to-peak voltage across capacitor. Increase the frequency slightl y to make sure there is no reduction in voltage. Increase frequency until the voltage is 0.707 of the low-frequency voltage. Measure the frequency on the oscilloscope (f = 1/period).
  4. May 26, 2015 #3
    I see yes.Thit is surely a relief.Your help is truly appreciated!
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