What happens when the potentiometer wire Is replaced with a copper wire?

A potentiometer wire of length L and a resistance r are connected in series with a battery of emf E_(0) and resistance 'r_(1)' . An unknown emf E is balanced at a length 'l' of the potentiometer wire. The emf E will be given by

When electric current is passed through a resis tance wire, it get heated up" What happens to the heat energy developed, if the current through the wire is doubled.

What happens to the Zn rod when dipped in copper sulfate solution?