(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

C = 1 uF

E = 12 V

Total R in circuit = 100 Ω

Q = 0 before the breaker closes

Problem A:

Derive an expression for the voltage across the capacitor and the current through the circuit as a function of time after the breaker closes.

2. Relevant equations

This is my first problem. I do not know any relavent equations.

3. The attempt at a solution

I have trouble starting this exercise, but from what I have found on Wikipedia, the capacitor needs 5τ to fully charge, and 1 τ = R times C.

From what I understand, the voltage across the capacitor will decrease until the capacitor is fully charged.

But that comes in conflict with my understanding about that a capacitor will have a voltage across when fully charged (maybe only when there is no other voltage sources present?)

Please kick me in the right direction here, so that I can get going :)

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# Very simple RC-circuit

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