What is the $SI$ unit of electric potential?

An electron in a metal is free to move anywhere but cannot leave the metal.

How does the resistivity of alloys compare with those of pure metals from which they may have been formed?

How many watt-seconds are equal to $1$ unit of electrical energy?

$A$ wire is $1.0 \, m$ long,$0.2 \, mm$ in diameter and has a resistance of $10 \, \Omega$. Calculate the resistivity of its material.

The applied potential difference across a given resistor is altered so that the heat produced per second increases by a factor of $16.$ By what factor does the applied potential difference change?