Specific resistance of a conductor increases with

For a cell terminal potential difference is 2.2V when circuit is open and reduce to 1.8 V when cell is connected to a resistance of R = 5 $$\Omega $$. Determine internal resistance of cell (r)

If specific resistance of a potentiometer wire is 10^-7$$\Omega $$ m and current flow through it is 0.1 amp., cross-sectional area of wire is 10^$$-$$6 m² then potential gradient will be

Copper and silicon is cooled from 300 K to 60 K , the specific resistance