While making a standard resistance. The coil is made of maganin. The coil is doubled folded and is wound over non- conducting frame.Why?

Explanation

For manganin, the temperature coefficient of resistance is very low. Due to it, the resistance of manganin wire remains almost unchanged with change in temperature. The resistivity of manganin is high. Therefore, for making a standard resistance of the given value, the smaller lenght of wires is needed. It is due to these facts, the wire of manganin is used for making stnadard resistance coil. The coil is double folded on itself to avoid the inductive effect and it is wound over the non-conducting frame in order to avoid the conductive effect and the leakage of current.