Hi, I have been having some issues regarding the current and voltage divider equations. The question requires me to use superposition to determine the voltage accross R3 which is 3k ohms, (the third resistor from the left).

Please see circuit : http://tinyurl.com/yb39qr4v

I had no issues finding the voltage via only the current source. Which is 4V and the falstad model agrees with me : http://tinyurl.com/ybhldcjz.

However when I used the voltage divider formula to find the voltage across R3 via only the voltage source, I started to notice some issues : http://tinyurl.com/y738leag

Firstly shouldn't the voltage be the same for R1 R2 and R3? However when I use the voltage divider rule I get various different answers. For example, I combined R1 R2 and R3 to give me 1.2 k ohms resistor which is connected to R4 (4k ohm). When using the voltage divider rule I get .69230 V. And the final answer should be 4V + .692V = 4.692 V. However the circuit here displays the voltage over R3 to be 5V. Why is this the case?

http://tinyurl.com/yb39qr4v

Please Reply Soon.

 

You need to know the voltage from the battery on the right hand side to do the calculations.

Les.