Question

Write down the nodal equation in a matrix form and determine the current flowing through branch AC.

Answer 1

Here is the circuit.

Answer 2

The answer is 2.6A.
I've worked it out first by using KCL and Ohm's law at the Nodes.
At that point I've considered current direction. Then, using Cramer's rule I got 12A.
If we don't take into consideration current direction, i.e take it all to be positive, you obtain the answer 2.61A.

Answer 3

However, i don't understand why we don't take the current directions in this case while using KCL. Can anyone explain me the reason why.

Answer 4

KCL - Kirchoff's current law

Answer 5

you dont take signal if current is entering in node or leaving it?

Answer 6

Yes. We don't consider whether it is leaving or entering the node, then we get the answer.

Answer 7

if you dont using the signal then you will find in your ans a negative current

Answer 8

if you do all you currents like this all will be positive,but when you do the equations some value will be negative get it?

Answer 9

So that's why we take it that all the current is moving away from the node..??

Answer 10

yes, you dont have to know first, the direction of current ,if you find a negative value the current is entering in node instead leaving

Answer 11

Okay..!! Thanks for your help..!! Fan + medal..!! :)

Answer 12

you are welcome