Here is your take home problem that is due on Friday of Finals Week. Please check this page occasionally to be sure that I have not had to make modifications to the problem. I haven't done all the details of the problem though I have roughed my way through it. If bugs are found I will note them on this page.
Communication is an essential tool - organize your work clearly!
1) The op amp circuit below has an input side and an output side. Read the questions carefully so you demonstrate the requested skills clearly in your answers to each part. If you get totally stuck at any point make up an answer that seems reasonable to you (would be nice if you justified your choice) and proceed to the next part.
I) Using Node Voltage techniques find the Thevenin equivalent voltage for the input circuit at a-b.
II) Using Mesh Current techniques find the Norton equivalent current for the input circuit at a-b.
III) What is the Thevenin equivalent circuit at a-b including the specific value of the equivalent resistance?
IV) Replacing the input circuit with its Thevenin equivalent circuit and determine the output voltage of the op amp. Be careful to note the place where the wires in the op amp circuit are NOT actually touching on the input side. Assume that this is an ideal physics op amp and that the output switch is not closed yet. If you have doubts about your results from I-II-III then choose a Thevenin source voltage and an equivalent circuit resistance that seem at least remotely plausible and proceed.
V) Having completed your brilliant analysis of the op amp behavior now close the switch and wait patiently until you are sure the output circuit has settled down. The output voltage of the op amp is whatever you determined in part IV). At t=0 open the switch and determine the time dependent behavior of the voltage across the 50 k resistor.
VI) So how long will you need to wait before the circuit settles down after you open the switch – either my rule of thumb or the books will do fine here as long as you clearly understand the concept.
VII) Go find a great book and a warm beach and relax --- you’re done with E Fundies!!!
