Wheatstone bridge principle and resistance?

Question

Why 4 resistance is used in Wheatstone bridge? Why not 3 or 2
resistance?Tell me reasons.

Answer 1

the wheatstone bridge consists of 4 resistors, 2 of them r known (constant), third one is known (variable), the fourth one is unknown & it can be calculated by the formula below
these 4 resistors must be connected to an electric source & galvanometer
we use 4 resistors becouse its a necessary condition to reach equilibrium in the wheatstone brigde is (R1/R2) = (R3/R4)

i hope u got ur point from my explanation

Answer 2

The name "Wheatstone" historically refers to a 4 resistor bridge. There are many other types of bridges that are not Wheatstones.

However, all true bridges have four main impedances. These impedances may be resistors, inductors, or capacitors.

For example, a capacitance bridge is comprised of two inductors, in the form of a ratio transformer, and two capacitors. One precision adjustable capacitor and one unknown capacitor.

Why is it always four impedances? A bridge is a pair of voltage dividers with each divider being comprised of two impedances. The objective of the bridge is to subtract two nearly equal large voltages (the outputs of the two dividers) to extract a small signal. Usually, one divider is adjusted so as to zero the difference signal.

Answer 3

A small change in resistance across the center connections of the bridge produces a large current flow. This makes for more easily detected resistance deviations.