How Does Doubling Frequency Affect R-L-C Series Circuit Components?

[meryom]

If the frequency of a source is doubled in a R-L-C series circuit,what will happen to the resistance ,the inductive reactance and the capacitive.

Homework Equations

f=1/2pi√LC
XL=2.pi.f.L
XC=1/2.pi.f.C
R=Vrms/Irms
i coludn't know which formula to use am confused please help ...

 

[gneill]

The RLC circuit is being driven by a source with frequency f. What are the values of the reactances for the inductor and capacitor? Does the resistor's impedance depend upon frequency?

Oh, and welcome to Physics Forums!

 

[meryom]

thanks :) ...sorry nothing else is given ...and i think it depend since z=√(xl-xc)^2+R^2
and xl=2.pi.(f).L and the same for xc=1/20pi.(f)c

 

[gneill]

You have enough information to answer the question. You've already written the required formulae several times!

If I were to ask you to write the formulas for the reactances of an inductor and a capacitor and the resistance of a resistor given that the frequency is f, what would you write?

XL(f) = ?
XC(f) = ?
R(f) = ?

 

[meryom]

i would write the above formulae ...so should i solve for frequency(by doubling it ) using the above formulae ?...what about for R ?

 

[gneill]

i would write the above formulae ...so should i solve for frequency(by doubling it ) using the above formulae ?...what about for R ?

The question asks you to state what happens to the reactances when the frequency is doubled. In order to do that, you must observe how the reactance values depend upon the frequency variable in the formulas.

Also, does R depend upon frequency? Is there any "f" value in the expression for resistance?

 

[meryom]

Also, does R depend upon frequency? Is there any "f" value in the expression for resistance?[/QUOTE]

i don't think so ..??

 

[gneill]

Also, does R depend upon frequency? Is there any "f" value in the expression for resistance?

i don't think so ..??[/QUOTE]

Right, an ideal resistor's value is independent of frequency. Now you know!

 

[meryom]

ok !really thank you , i get it now ... ;)