Calculation of Kirchhoff Current Law.

In previous post, we learn how to calculate voltage,current and resistance by kirchhoff voltage law and ohms law. So now, we going to learn about calculation of kirchhoff current law. Get ready with your genius mind and Lets do some mathematics.

KIRCHHOFF CURRENT LAW : THE SUM OF CURRENT FLOW INTO NODE AND FLOW OUT TO THE NODE ARE EQUAL TO ZERO.

Let's look some examples of kirchhoff current law to understand further into.

The picture above shown is current flows into and flows out of the node. Calculate the  value of current 'X' ?

To understand the flow of current into and out to the node, we should know which direction the current flows. If the current flows to the node, the direction will be positive. If the current flow out from the node, the direction will be negative. So based on the picture, the current flows to the node is 1A,4A, and X. The current flows out from the node is 6A and 3A.

The equation will be :

1A+4A+X-6A-3A=0

                  X-4A=0

                              X=0+4A

                          X=4A 

Easy right!!!. In kirchhoff voltage law or current law you should know which direction the current flows.Then you will know how to calculate the problem of a circuit. Lets look another example.

The picture above shown is current flows in and out in two node. Calculate the value of current of I3.

 

Now as you the picture I1 and I2 flows into node A so calculate the current for node a is

 

A= I1+I2 

A= 1.5A+2.7A

A= 4.2A

 

The value of current at node a is 4.2A.Now in order to calculate the I3, the current of node A is flows to B. So the calculation is :

 

(I1+I2)+I3+I4=0

4.2A+I3+3.3A=0

I3=0-3.3A-4.2A

I3= -7.5