# Need help with RLC circuit please

Discussion in 'Homework Help' started by difx0, Apr 5, 2010.

1. ### difx0 Thread Starter New Member

Apr 5, 2010
3
0
Have this question that is part of my school assignment. Finished all the others but this is just beyond me.

To do with RLC Circuits as from the research I have done on the web, there are many similar problems but not quite like mine.

From the circuit above...

Calculate the following parameters for the circuit above, VL , VC, VR1 and VR2.

Also Calculate the current IL, IR1, IC and IR2.

And finally determine the phase angle between the supply voltage and current flowing in R2.

If anyone can help me with even one of the answers, would be VERY grateful.

2. ### jlcstrat Active Member

Jun 19, 2009
58
3
Do you know how to do polar or rectangular math?

3. ### Engr Member

Mar 17, 2010
114
5
Try replacing C1 with Xc and L1 with XL. Then try solving using Rectangular and Polar Math.

4. ### difx0 Thread Starter New Member

Apr 5, 2010
3
0
I do know about rectangular and polar math, however I am not sure how to solve these still, what formulas to use etc

can anyone please work out one of the unknowns that is asked for?

Would be very very greateful

5. ### Engr Member

Mar 17, 2010
114
5
For the capacitor the capacitive reactance is -jXc while for the inductor the inductive reactance is jXL. Xc can be calculated using this formula Xc=1/(2*pi*f*C) while XL can be calculated using this formula XL=2*pi*f*L. If you already have this values solve the total resistance first. Using the Xc and XL values the total resistance can be solved using the formula when solving the total resistance of a resistor, the only difference is that you will be using the rectangular and polar math when solving the total resistance.

6. ### difx0 Thread Starter New Member

Apr 5, 2010
3
0
That does help, but can someone please work out the Total Impedence of the circuit for me. (The Z Value)

would be very much appreciated

7. ### shteii01 AAC Fanatic!

Feb 19, 2010
3,297
482
Replace the C1 with $\frac{1}{sC}$. You now have two "resistors" in series, Req1=R2+$\frac{1}{sC}$.

Req1 is in parallel with R1. Req2=$\frac{R1*Req1}{R1+Req1}$

Replace L1 with sL. Now you have two "resistors" in series, sL+Req2. This sum is the total resistance of the circuit, Z.

s=jω
ω=2πf
f=1000 Hz