Short and open circuits:

In network simplification technique short and open circuit existing in the network plays an vital role

Short Circuit:

When any two points in the electrical network are connected or joined directly to each other with a thick metallic conducting wire then the two points are said to be short circuited

The resistance of the short circuit is zero

The part of the network which is short circuited is shown below

Points P and Q are short circuited and the resistance of the branch PQ is Rshortcircuit=0

The current PQ is flowing through the short circuited path is given by ohms Law:

VPQ=RshortcircuitX IPQ

=0XIPQ

=0V

Thus the voltage across the short circuit is always zero though the current flows through the short circuited path

Open Circuit:

When there is no connection between two points of the network and having some voltage across the two points then these points are said to be open circuited.

The resistance of such circuits will be infinity as there is no connection between the points.

Open circuited example is shown below:

The points P and Q are said to be open circuited and the resistance between them Ropencircuit is infinity ohms.

According to Ohms Law-

Iopencircuit=VPQ/Ropencircuit

As we know open circuit resistance is infinity so

Iopecircuit=0A

Hence current through open circuit is always zero there exist a voltage across open circuited terminals.