# Homework Help: AC Circuits

1. May 3, 2009

### steveironpump

1. The problem statement, all variables and given/known data

In an L-R-C series circuit, L = 0.270 H and C = 3.80 µF. The voltage amplitude of the source is 120 V.
(a) What is the resonance angular frequency of the circuit?

2. Relevant equations

Xc = 1/(wC)

XL = wL

w=angular frequency

3. The attempt at a solution

I couldn't get anywhere. I know that I have to do something with the voltage, but I have no clue

2. May 3, 2009

### nickjer

Well you want the magnitude of the impedance to go to 0. And since they are both 180 degrees out of phase with each other and in series, you treat them like vectors and subtract them. Then solve for $$\omega$$.