Question

If you were given a hardwired RC circuit with unknown values for the resistor and capacitor (and did not have a DMM to measure the resistance or capacitance), write up a procedure for how you would determine the range of frequencies sufficient to collect data in order to graphically determine the cutoff frequency.

Answer 1

First of all connect a sinusoidal voltage source of known frequency .

Then measure the voltage across resistance which is $V_R=IR$

and voltage across capacitor will be

$V_C= \frac{1}{j \omega C}$

Now from the equation

$V_s^2=V_R^2+V_c^2$

Now we can easily calculate R and C

and cutoff frequency

$f_c=\frac{1}{2 \pi RC}$