# Homework Help: Energy in Circuit between load

1. Aug 2, 2007

### Trooko

1. The problem statement, all variables and given/known data
All components arranged parallel,

voltage source =10sqrt(2)cos(2000t)
10 ohm resistor, 10mH inductor, 15 microF
How much energy is exchanged between the source and the load? (book answer: 0.0962J) Between the capacitor and the inductor? (0.144J)

But I think the book answer made a mistake in getting Z_eq which gave the wrong anwer. I think they left Z_eq invert and used it as Z_eq in calculation

2. Relevant equations
I_p = V_p / Z_eq
S =0.5 (V_P) (I_P*) -> giving a complex solution, where the real is P and im is Q

Between source and load: W = Q/omega
Energy in inductor W = (0.5)( L )(I_P)^2
energy in capacitor W = (.5) (C) (V_p)^2

3. The attempt at a solution

Find the Z_eq by adding the admittance of the components, then invert it giving 9.8 with degree 11.3

Find I with the equation above 1.02 sqrt(2) degree -11.3

Find S giving Real(10) + Im(2) -> p=10 Q = 2

Energy between load and source: using omega = 2000 -> W = 2/1000 = 0.001

Energy between capacitor and inductor: I think it should be the energy of the inductor plus capacitor
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Aug 3, 2007

### Mindscrape

Is the load supposed to be the whole network, the resistor, or something else? Also, I think you are correct that it wants the energy of the inductor plus the capacitor.

3. Aug 3, 2007

### Trooko

Yes, The load consist of the resister, inductor and capacitor.