Transient analysis for a simple circuit (simulation disagreement)

[mr_monster]

I'm given this circuit:

The switch is open for a long time (so steady state is reached). at t=0 the switch closes and at t=1 usec the switch opens up again.

So here are the highlight in my analysis and where simulation using Multisim disagrees with me.

Before t=0, the voltage across the cap is 10V. After the switch closes the voltage across the cap "wants" to get to 5V, however tau is too large so in the short 1 usec the switch is closed we can say the voltage across the cap does not change, however during this short time the voltage across R3 does change as some current flows through it (3.75mA). So just after t=0 the voltage across R3 is 7.5V, this current is the result of the cap discharging. Multisim disagrees and shows the current across R3 is always 0 since the cap voltage is same as the power supply so no current runs through there anyway, however the voltage alteration across the resistor should be instantaneous for the purpose of this analysis.

So which one?

 

[crutschow]

You simulation appears to be in error. Since I don't know how you simulated it I can't comment on what the error might be. Can you post your simulation circuit and the results?

Do you mean the current "through" R3 is always 0 in the simulation?

 

[mr_monster]

Here is the schematic, the graph that Multisim outputs and the setup I use for the analysis, which is the default but with a shorter time period. You can see that I alter the switch using a PWL voltage source. The program does show the voltage falling across the cap as soon as the switch closes but you can see the line on the bottom does not move even a bit.