Tough Question

[Dean820]

Here's a question I got for homework and I really do not have a clue on how to do it. Even if somebody could do pieces of it, I would be most grateful.

A capacitor© of 10 μF is connected in series with a resistance® of 5kΩ across a 20 V

d.c supply (E). Calculate

(i) The initial charging current.

(ii) The initial voltage across the capacitor.

(iii) The Time Constant (T) of the circuit.

(iv) The voltage and current at the Time Constant.

(v) The voltage across the capacitor after 75 milliseconds

(vi) The time for the current to reach 2 mA.

(vii) The time for the voltage to reach 18 V.

(viii) The voltage on the capacitor after a long time period.

 

Note : The charging current in the circuit is given by i(t) = (E/R) e^-t/CR.

 

The charging voltage across the capacitor is given by v(t) = E(1- e^-t/CR).

[swansont]

Here's a question I got for homework and I really do not have a clue on how to do it. Even if somebody could do pieces of it, I would be most grateful.

A capacitor© of 10 ?F is connected in series with a resistance® of 5k? across a 20 V

d.c supply (E). Calculate

(i) The initial charging current.

(ii) The initial voltage across the capacitor.

(iii) The Time Constant (T) of the circuit.

(iv) The voltage and current at the Time Constant.

(v) The voltage across the capacitor after 75 milliseconds

(vi) The time for the current to reach 2 mA.

(vii) The time for the voltage to reach 18 V.

(viii) The voltage on the capacitor after a long time period.

 

Note : The charging current in the circuit is given by i(t) = (E/R) e^-t/CR.

 

The charging voltage across the capacitor is given by v(t) = E(1- e^-t/CR).

 

 

You have the equations. What do you get when you put t=0 into them? That answers the first two. The fourth is just as straghtforward, as should be the last. vi and vii will require you to take the natural log at some point while solving for t.