1. Physics fuuu

I need to know why a fully charged capacitor can stop the current in a parallel pathway.

Yes, I tried Googling. I really can't find a problem similar to this.

The currents in all of the resistors are for some reason stopped when C1 and C2 are fully charged. I think I can understand when the current in R3 is stopped, but not R1 and R2.

Never mind, got it. I think I'll keep this thread open though for more physics problems in the future.

2. Re: Physics fuuu

Okay, I give up. It does not make sense. There's nothing that the capacitors can do to terminate the potential difference across the emf's terminals, and the terminals are always connected by the conductors (wire/resistors). How come the current stopped?

3. Re: Physics fuuu

you had them lined up right?

4. Re: Physics fuuu

When fully charged, a capacitor's voltage equals that of the source charging it (in this case, both C1 and C2 when added together = E's voltage). When you apply Kirchoff's Loop and Junction rule and use this method to determine the voltage of the loop, you get three equations that are equal to zero (Since one of the sides ends up as E - C1 - C2, but that is zero as defined previously).

Thus, if you put all of them into a matrix and solve for each of the values, there is no valid rule of matrix manipulation that would allow you to get a non-zero answer for any of the currents.

Therefore, no current in the circuit flows (if there is no leakage) when the capacitors are fully charged.

5. Re: Physics fuuu

Thanks for reminding me of Kirchoff's Loop and Junction rules, I missed my days of Physics 2.
The capacitors charge with an exponential approach function =D

6. Re: Physics fuuu

@Kalovale @MuscleWizard @WayOfTime @Shidoshi By a freak turn events, it is not actually 0.

7. Re: Physics fuuu

Just got to this today. Solved this problem right out of class with the new tools. Haha.

8. Re: Physics fuuu

Did you miss my post that it's not actually 0?

9. Re: Physics fuuu

Using the Kirchoff's Loop thingy should still work. I haven't done the calculations myself though. It has been too long since I last used this.

10. Re: Physics fuuu

My best attempt.

That result essentially means once the capacitors are fully charged, the circuit becomes R_1 and R_2 in series, which agrees with my initial hunch.

11. Re: Physics fuuu

Ah, yeah.

That was my initial hunch too.

Damm trusting people who say they checked their answer with the teacher ha ha.

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