# Ideal Voltage Source Short Circuited in exam problem

V2 in the diagram is the same as Vin,so it is not 5V constant but it follows the graph.

In an exam question I was given the circuit depicted in the image.The prompt went like this: In the circuit below switches (1) and (2) remain closed for the time period that Vin == 5V. (a) Calculate the voltage across the capacitor for t>= 0 and graph it. (b) Relate the time constants of the circuit for t in [10 ms,inf) and explaing their values circuit wise.

My question is what happens when switch 2 closes.The ideal voltage source V2 will be short circuited and then I don't know whether the voltage across its terminals is going to be 0 (short circuit) or 5V as the graph that was given indicates.My professor insists that Voltage source V2 does not affect the circuit and hence we treat it as a short circuit.I will be glad to read your answers.

• -1 for your professor for asking a stupid question. Commented Jul 16, 2022 at 12:45
• Thank goodness we have circuit breakers - I hope your professor is not an experimentalist. Commented Jul 16, 2022 at 13:42
• it's a trick question ... there is no source of Vin connected to the circuit ... that means only V2 varies Commented Jul 16, 2022 at 16:50
• It seems to me that my professor "wanted" a voltage controlled switch but couldn't use the notation cause it wasn't taught during the course,so she abused ideal notation.To my understanding this circuit would blow up.Correct me if I am wrong. Commented Jul 17, 2022 at 16:40