Question

ODE's/Electrical Eng'g: Find v(t) for the RLC circuit in this picture: http://dl.dropbox.com/u/17638088/rlc%20overdamped.PNG given v(0+) = 12 V, and i_L(0+) = 30 mA.

Answer 1

Using what I've learned in my ODE class, solving the 2nd order differential equation v'' + (1/RC)v' + (1/LC)v = 0 for this situation gives a different solution from my textbook's solution for some reason..

Answer 2

This is what I did: http://www.wolframalpha.com/input/?i=x%27%27+%2B+%281%2F%28%280.2*10%5E-6%29*200%29%29x%27+%2B+%281%2F%28200*50*10%5E-3%29%29x+%3D+0%2C+x%27%280%29+%3D+-450000%2C+x%280%29+%3D+12

Answer 3

i was doing the same :P

Answer 4

But the book has v(t) = -14e^(-5000t) + 26e^(-20000t) though..

Answer 5

L=?, C=?

Answer 6

R=?

Answer 7

L = 50mH, C = 0.2uF, and R = 200 Ohms as shown on the picture

Answer 8

http://www.wolframalpha.com/input/?i=x%27%27+%2B+%281%2F%28%280.2*10%5E-6%29*200%29%29x%27+%2B+%281%2F%28%280.2*10%5E-6%29*50*10%5E-3%29%29x+%3D+0%2C+x%27%280%29+%3D+-450000%2C+x%280%29+%3D+12

Answer 9

you messed up C on the last

Answer 10

oh lol thank you.. I did LR instead of LC haha thanks