# Series RLC - calculate V w/ different ƒ

1. Apr 24, 2015

### dwn

1. The problem statement, all variables and given/known data
Series RLC - Band Pass Filter

R = 2700Ω
Vi = 5 Vpp
C = 10 nF
L = 33 mH
I need to find the voltage across the resistor for different frequencies.
2. Relevant equations
w = 2pi*ƒ
V = R*Vi / (jwL + 1/jwC+R)

3. The attempt at a solution
This is from a lab experiment. How can I use the source voltage, R and ƒr to find the voltage across R at different frequencies.

-----update -----

Last edited: Apr 24, 2015
2. Apr 24, 2015

### Staff: Mentor

You haven't given all the information required: What are the values of L and C?

3. Apr 24, 2015

### Staff: Mentor

Your relevant equations are indeed relevant. You've correctly written a voltage divider equation which will give you the voltage across the resistor for values of Vi and f. Of the the result will be a complex value. You might try reducing it to magnitude and angle (polar) form. In the lab, what device (test equipment) was used to read the output voltage?

4. Apr 24, 2015

### dwn

We used an oscilloscope to read the measured values, now I have to calculate the data with the given data for comparison. Then find the percentage error.

5. Apr 24, 2015

### Staff: Mentor

Okay. So you'll have recorded values for the waveform peaks, thus the voltage magnitudes, for various frequencies. You can use your voltage divider equation to calculate the voltage and determine the theoretical magnitude values. Again, you might want to reduce the formula to a magnitude version.