How Do I Calculate the Charge Over Time in Simple RC Circuits?

[stephencohorn]

Ok, if I have a Battery B, Resistors R1, R2, and Capacitor C in this circuit:
(the ...'s just represent empty space, spaces were getting eaten when I previewed the post)

|----------R1--------|
|......|
B+......|
B-......C
|......|
|---------R2---------|

is this equivalent to:

|--------R1--------R2---|
|.......|
B+......C
B-......|
|.......|
|------------------------|

if not, how would you get the charge as a function of time for the first circuit?
also, how would you get the charge as a function of time for the following circuit?

|---------------|---------|
|.....|....|
|.....C...|
B+......|...R
B-......R...|
|.....|...|
|-------------------------|

any conceptual comments on how these two would compare speaking of rate of chargeing, final charge, etc?

Any help would be appreciated, I'm struggling with this stuff.
Thanks,
Stephen

 

[elyes]

please can you help me to solve my problem

 

[stephencohorn]

can anyone help me out?

 

[berkeman]

Combining R1 and R2 in the first circuit to make the 2nd circuit is fine, if you are wanting to calculate the capacitor voltage versus time.

For the 3rd circuit, you will need to write the KCL equations for each of the nodes, including the node between the bottom R and the capacitor.