What is Wheatstone Bridge verify it's balance condition [ Class 12 Electric Circuit.]

 

Wheatstone Bridge 

It is electric circuit helpful to find unknown resistance among four resistance.

It is an arrangement of four resistor such that if we know the value of  the resistance of any three of them , we can obtain the value of fourth unknown resistance.

In the circuit Let's suppose four resistors with Resistance R_(1) R_(2) R_(3) and x respectively. R_(1) R_(2) R_(3) is known resistance where as X is unknown resistance whose value is to be determined.

The cell with emf 'E' and current I is connected.The amount of current flowing through R_(1) ,R_(2), X ,R_(3) are I_(1) I_(2) I_(4) and I_(3) respectively. C and D are connected along with galvanometer , where amount of current flowing is I_(g) .

The bridge is said to be balanced when deflection in galvanometer is zero. I.e (Ig=0) potential C and D is same .

Hence, we can obtain the value of unknown resistance x from above relation.

Fig .Wheatstone bridge