The mistake, you shouldn’t do while applying Node Analysis

Node Analysis is one of the most important network simplification techniques that we use. Let us see the number 1 mistake, most of the students do while solving the sums with Node Analysis.

What is Node Analysis?

Node Analyis is a powerful network simplication technique where we write the KCL equations for various nodes in the circuits. Then we solve the equations to find unknown node voltages. Once we get the node voltages, we can easily get current or P.D. of any branch.

What is KCL?

Node Analysis basically depends on Kirchoff’s Current Law. It is the fundamental law in Networks which is applied for a given node.

It states that at any node of the circuit, sum of all the currents is always zero.

For example, consider following node of the circuit where 5 currents are meeting (entering or leaving).

So, sum of all these 5 currents must be zero. But we have to write these currents with proper sign convention.

Sign convenstion says, take all the incoming currents as positive while outgoing currents as negative. Or you can take vice versa, i.e. incoming currents negative and outgoing currents positive.

So, if we follow incoming currents as positive while outgoing currents as negative then the KCL equation would become as follows,

I_1+I_2-I_3-I_4+I_5=0

Even if you follow other one i.e. incoming currents negative and outgoing currents positive, still you will get the same equation.

And here is the mistake students do while solving for Nodal Analysis.

You have to stick to any one of the convention for entire numerical. If you take incoming currents as positive and outgoing as negative then you must take it same for the given node.

You should also carry the same convention for other nodes of the circuit to avoid any mistake.

Keep it simple and avoid the mistakes.