- #1

Vanush

- 25

- 0

hi all, wonderign whether you can help with this problem with capacitor discharging.

take a look at the pic

the question is

In the circuit shown above, the switch has been in the upper position for a long time and moves to the lower position at t = 0. Find i(t).

Basically, first i wanted to find out wat the voltage between the capacitor terminals would be after the long time it had been in the upper position. I found this as 20/3 V using thevenins theorem. now, i(t) is given in the textbooks as [-V*e^(-t/RC)]/R where V is the voltage across the OC capacitor. however, the discharge circuit the capacitor is connected is not just a simple circuit which contains only resistors - it contains a voltage source. how can i get an expression for i(t) in the discharge circuit? or am i going about this the wrong way.

thank you.

EDIT: I am not supposed to post this here, but i can find no way to delete the thread?

take a look at the pic

the question is

In the circuit shown above, the switch has been in the upper position for a long time and moves to the lower position at t = 0. Find i(t).

Basically, first i wanted to find out wat the voltage between the capacitor terminals would be after the long time it had been in the upper position. I found this as 20/3 V using thevenins theorem. now, i(t) is given in the textbooks as [-V*e^(-t/RC)]/R where V is the voltage across the OC capacitor. however, the discharge circuit the capacitor is connected is not just a simple circuit which contains only resistors - it contains a voltage source. how can i get an expression for i(t) in the discharge circuit? or am i going about this the wrong way.

thank you.

EDIT: I am not supposed to post this here, but i can find no way to delete the thread?

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