Wheatstone Bridge and Meter Bridge

WHEATSTONE BRIDGE

If R_x is the unknown resistance to be measured and R₁, R₂ and R₃ are resistors of known resistance and the resistance of R₂ is adjustable. Using the principle of wheat stone bridge network when (R₂ / R₁) = (R_x / R₃), then the voltage between the B and D will be zero and no current will flow through the galvanometer. R₂ is varied until this condition is reached.

At the point of balance, the ratio of R₂ / R₁ = R_x / R₃

Therefore,