0:00
31 .60.
00:02
So we have an rlc circuit that's being driven here.
00:06
These are the values of all the things and at 0 .442 milliseconds we want to determine what the power being delivered by the our power source here is, or the generator or whatever, and then we want to find the power in the capacitor, the inductor and the resistor and then determine whether the sum of these is equal less than and or greater to the power that the generator is delivering.
00:36
So first what we want to do is determine the current in the circuit.
00:52
It's going to be the same for all of the elements because it's a serious circuit.
00:59
So the impedance is going to be the usual formula here.
01:06
R squared plus omega d l minus 1 over omega dc squared squared.
01:24
Close up our square root, try not to run out of space vertically.
01:36
All right.
01:42
So this works out to 1 .93 amps, and the phase is the arc tangent of the inductive reactants minus the capacitive reactants divided by the resistance.
02:14
This would be 46 .5 degrees.
02:22
And so the current is a function of time.
02:27
Will be i sine omega d t minus the phase and we saw we just found the amplitude of the current and the phase so now the power is applied by the generator is just the current at that time times its voltage at that time is going to be i times e sub m times a sign of omega t minus phi times a sign of omega t minus phi times a sign of omega t.
03:34
So we know what all of these are.
03:35
Omega's are 3 ,000 radiance per second, t .442 milliseconds, 5, 46 .5 degrees, etc.
03:46
So we find 41 .4 watts.
04:03
So now for the capacitor, the voltage across it is b, sub c, sine of omega d t minus phi, minus the pi over two radiance.
04:30
We get from a capacitor negative ec cosine omega t minus phi and the amplitude of this ec is just i over omega c so now the rate at which we're adding energy to the electric field in the capacitor is the rate at which the energy is changing this is the energy in a capacitor.
05:27
Now the derivative of the charge is the current...