(i) The connections are made of thick copper wires to minimize the resistance of connecting wires. Because the connection resistance have not been accounted in the formula, (v Resistance is inversely proportional to cross-sectional area, so thick wire has low resistance).
(ii) The error in the measured value of unknown
resistance 5 using bridge wire will be minimum, when the null point is obtained at the middle of bridge wire. In this situation, the end error of the bridge will be ineffective.
(iii) Alloys, such as manganin or constantan are used for making meter bridge wire due to their low temperature coefficient of resistance and high resistivity.