Discuss Can you work out the value of the resistor? in the Electrical Forum area at ElectriciansForums.net

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thepipersson198

Hi guys,

Just wondering if you can help me on this one,

I have a RLC series circuit the values are as below;

R = unknown
L = 800mH
C = 300uF

from there I have calculated;

the resonant frequency to be 10.3Hz
the capacitive reactance 51.50 ohms

The reason I need to know is I need to work out the impedance, which is

Z= sqrt^R^2+(Xl-Xc)^2

So I have the following,

R is unknown
L is 800mH
C is 300uF
F = 10.3Hz
W = 2pie*F
Xc = 1/WC
Xl = WC

So If there is a way i could work out what the resistors value is, then I can work out what the impedance is, but please bear in mind this is just a paper exercise, so I have no tools i can use to determine this for me.

Many thanks for your help in advance
Tom
 

Marvo

Admin and gender confused
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If you're currently on a training course you can get access to our Trainee section which you might find helpful.

Check out this thread, do the necessary and access will be granted if you qualify.
 

Lucien Nunes

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You have too many unknowns. If you knew the resistor value you could calculate the impedance at a given frequency, or vice versa, but at the moment you have neither so cannot calculate anything.
 

happysteve

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Do you know the Q factor of the resonant circuit? If so, you could work out R using:

Q = (2 x pi x f0 x L) / R

... or ...

Q = 1 / (2 x pi x f0 x C x R)

(where f0 is your resonant frequency)
 
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