Electrical Bridge Networks

Bridge circuits are widely employed in Electrical and Electronics Engineering for measurement purposes. In this post, you’ll learn about electric bridge networks.

How it looks

The figure below displays a 5 resistor bridge network:

It can also be redrawn as:

Balanced vs unbalanced bridge

In above figure if R1/R3 = R2/R4 then bridge is referred as balanced bridge. If the ratio R1/R3 is not equal to R2/R4 then bridge is referred as unbalance bridge.

In a balanced bridge the current flowing through R5 is zero.

Example: Find the current flowing Rs in bridge network shown below.


Since R1/R3 = R2/R4, zero current passes through R5.

Here we can replace the resistance R5 by an open circuit.

The overall resistance Rs through circuit is:

Rs = 10 Ω + {(2 Ω +4 Ω )||(6 Ω + 12 Ω )} = 10 Ω + 4.5 Ω = 14.5 Ω

I (Rs) = V/Rs = 24/14.5 Ω = 1.65 A

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