Find Resonant Frequency of L-R-C Series Circuit

In summary, the resonant frequency of a L-R-C series circuit containing a 1x10^-6 F capacitor, a 7.00 mH coil and a 90 ohm resistor can be calculated using the formula f=(1/Xc)/2pi*C, where Xc is the reactance of the capacitor. It is important to note the difference between resistance and reactance when solving for the resonant frequency.
  • #1
jakeowens
34
0
A L-R-C series circuit contains a 1x10^-6 F capacitor, a 7.00 mH coil and a 90 ohm resistor. What is its resonant frequency?


For this one I used the formula for capacitive reactance.

Xc=1/2pi*fC

After doing some algebra i isolated the frequency giving me :

f=(1/Xc)/2pi*C.

So i substitute all my values giving me:

f=(1/90)/2pi*1x10-6F...

The answer i get seems really wrong. Did I use the wrong formula?

Should i have used XL=2pi*fL?

I'm really at a loss for what to do with this problem

any help would be appreciated
 
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  • #2
The resonance comes about because of the two energy-storing elements, the inductor and the capacitor. To figure out the resonant frequency, concentrate on the L and the C.

Hint, where are the reactance (complex impedance magnitude) of the inductor and capacitor equal?
 
  • #3
right... and one more thing ... you seem to have substituted 90 for Xc ...
90 ohm is the resistance of the resistor given.. But Xc is the reactance of the capacitor ...

they are two different things
 

1. How do I determine the resonant frequency of an L-R-C series circuit?

The resonant frequency of an L-R-C series circuit can be determined by using the formula: f = 1 / (2π√LC), where L is the inductance in henries, C is the capacitance in farads, and π is approximately 3.14.

2. What is the significance of the resonant frequency in an L-R-C series circuit?

The resonant frequency is the frequency at which the impedance of the circuit is at its minimum. This means that the circuit will experience maximum current flow at this frequency.

3. How can I experimentally find the resonant frequency of an L-R-C series circuit?

To experimentally find the resonant frequency, you can use an oscilloscope and a signal generator. Connect the signal generator to the circuit and adjust the frequency until the voltage across the circuit is at its maximum. This frequency is the resonant frequency.

4. What factors can affect the resonant frequency of an L-R-C series circuit?

The resonant frequency of an L-R-C series circuit can be affected by the values of the inductance and capacitance, as well as external factors such as temperature and humidity.

5. Can the resonant frequency of an L-R-C series circuit be changed?

Yes, the resonant frequency of an L-R-C series circuit can be changed by altering the values of the inductance or capacitance. Additionally, the resonant frequency can also be changed by introducing external factors such as a magnetic field.

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