2. Wheatstone bridge:

Figure 2.7.3 Configuration of a Wheatstone bridge

Wheatstone bridge is used to convert a resistance change detected by a transducer to a voltage change. Figure 2.7.3 shows the basic configuration of a Wheatstone bridge. When the output voltage Vout is zero then the potential at B must be equal to D and we can say that,

(2.7.1)

I1 R1 = I2 R2

(2.7.2)

Also,

Vbc = Vdc ,	(2.7.3)
I1 R2 = I2 R4	(2.7.4)

Dividing equation 2.7.2 by 2.7.4,

R1 / R2 = R3 / R4

(2.7.5)

The bridge is thus balanced.