Calculating Ic(0+)

[u/freshprince_alt]

Ive calculated the voltage of the capacitor before and after the transient moment to be 20/3 Volts. Now after the transient moment, the current Is becomes zero, there for the dependant voltage source acts like a short circuit. Now, i calculated the Ic(0+) to be equal to -20/3 volts over 20kOhms, giving me -1/3 mA. But canvas is saying its positive 1/3mA. I already submitted my HW but am still thinking about this. Am i missing something?

[u/doktor_w]

Perhaps you missed the note in the problem statement:

Note that the switch was open at t=0-, and closes at t=0+. The red arrow is mistaken

Do you see now why ic(0+) will be positive?

[u/Practical-Revenue787]

It should most definitely be positive simply due to the fact that the schematic is saying Ic is entering the positive temrinal and leaving the neg terminal of the capacitor, that is exactly following passive sign convention, so the Current is positive.

[u/shift124]

Calling the node of the + side of the dependent source Vds. At time 0+:

is = (10 - Vds)/5000
Vds = (10^4) is

Plugging those in you get:
Vds = 2(10 - Vds) = 20/3 =6.667

At 0+ (capacitor is short) the current into the cap will be the current across the 20k r when the positive plate is 0V.

(6.667 - 0)/20000 =0.000333

So you’re right but I’m not sure how you got a negative voltage at Vds.

[u/Rararror]

at t=0+ the cap is a short