Why do we use  manganine wire in potentiometer?

We know that potentiometer is used to measure potential difference. A wire made of manganin has very low temperature coefficient of resistance.

We also know that the voltage drop V across the potentiometer is directly proportional to the length l of the wire.

That is V ∝ l

Hence resistance may reduce the potential drop if copper or any other material with high temperature coefficient of resistance is used to make the potentiometer wire.