Q.Write the name of a device that does not follow Ohm's law.

A device is called OHMIC (or linear) if its current-vs-potential-difference (I-V) graph is a straight line passing through the origin, meaning its resistance $R=V/I$ is one single constant value regardless of how much voltage or current is applied. Simple metallic conductors -- for instance nichrome wire, used in heating elements -- are ohmic to a very good approximation over a wide range of operating conditions. …