Question

If we have given three resistances, current and voltage...how we find the 4th resistance

Answer 1

Answer

According to physics

A Wheatstone bridge is an electrical circuit used to measure an unknown  resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown resistance.

Wheatstone bridge circuit diagram. The unknown resistance R_x is to be measured; resistances R₁, R₂ and R₃ are known, where R₂ is adjustable. When the measured voltage V_G is 0, both legs have equal voltage ratios: $\frac{R_2}{R_1} = \frac{R_x}{R_3} and\\ R_x=\frac{ R_3}{R_2}{R_1}$