Question

Derive wheat stone bridge balancing equation​

Answer 1

As shown in the circuit diagram, there are four resistances connected as a bridge circuit. The three resistors R1, R2 and R3 will have known values. The value of the resistance RX will be unknown and has to be calculated. The value of resistance R2 is adjustable. A galvanometer has to be set between the points B and D.

The condition to be satisfied at the point of balance is given below.

If R2/R1 = RX/R3, then VBD = 0 and current through VG = 0. To reach this condition, the adjustable resistor is varied. The direction of the current can be known from the value of the resistor R2.

As soon as the balance condition is obtained the value of the resistance RX is obtained.

Thus, RX = [R2/R1] x R3

This method is very accurate as the other values of resistors are of high precision.