Ohmic Device: An ohmic device is one that follows Ohm's Law, meaning its resistance remains constant regardless of the applied voltage.
Non-Ohmic Device: A non-ohmic device does not follow Ohm's Law and its resistance changes with the applied voltage.
Conductivity: Conductivity refers to how easily a material allows electric current to pass through it. It is the reciprocal of resistance and is measured in siemens per meter (S/m).