Question

Using Kirchhoff's laws, obtain the equation of the balanced state in Wheatstone Bridge.

Answer 1

The Wheatstone Bridge is as shown in the figure

Applying Kirchhoff’s II law to mesh ABDA

I₁P + I_gG – I₂R = 0   ...(1)

For the mesh BCDB

(I₁ − I_g)Q + [−(I₂ + I_g)S] + [−I_gG] = 0   ...(2)

When the bridge is balanced, no current flows through the galvanometer

i.e. I_g = 0   ...(3)

∴ From equations (1) and (2) and (3)

I₁P = I₂R   ...(4)

I₁Q = I₂S   ...(5)

From equations (4) and (5),

`P/Q = R/S`