ENGR 221 - Lecture 13 - Transient Analysis of First Order Circuits

[@michaeljohnson1012]

Good 1 prof Thanks

[@bobcocampo]

what happens if inductance is shorted?

[@Jnglfvr]

Your calculation at 1:02:30 is wrong. Rth cannot be calculated based upon this circuit because the circuit, itself, is OVERDETERMINED. Please let me explain. For simplicity I'm going to put a 10K test source (to make the math easy). That means that the voltage across the 0.6*(i1) current source is also 10k. So we have 0.6*(i1) = 10k.or i1 = 10k/0.6 = 16.66k Now it is also true that there is 10k across that series (10k + 20 K resistor). So we have i1 = 10k/(10k + 20k) = 0.333 A. Do you see where the i1's don't match up because the circuit has no solution? You are free to use any value of Vtest that you like and will come to the same conclusion.

[@Jnglfvr]

Addendum to my note above: To resolve this problem you may put a small resistance in series with the test source (say 0.0001 ohm). In that case you will find that Rth = 10K.