# Homework Help: Calculate the energy stored in Capacitor and Inductor

1. May 13, 2012

### ckboii89

1. The problem statement, all variables and given/known data
A circuit consists of an 800mH inductor, a 20mF capacitor, and a switch, all in series.The capacitor is charged with an initial charge charge of Q = 400mC, and the switch is closed at t= 0.
Calculate the energy stored in the Inductor and Capacitor at t = 100ms.

2. Relevant equations
U= 1/2LI^2 + 1/2Q^2/c
I=Q/(LC)^1/2

3. The attempt at a solution
I= 3.16A
U=7.94J, there is no anwser key, it is a past exam that i do not have a key for. I feel i may have done this incorrectly since its asking for at t = 100ms, and U as a function of time is a sin/cos graph....

Last edited: May 13, 2012
2. May 13, 2012

### Staff: Mentor

You haven't supplied a complete problem statement; there's no circuit or component values.
Your Relevant Equation isn't an equation.
Your Attempt at a Solution isn't an attempt at a solution; if you provide a complete problem statement and your attempt, then we will know how to help.