A voltage-current graph for a thermistor is shown below. Voltage - Current graph for a thermistor as current and temperature rise.

The filament lamp does not follow Ohm's Law. Its resistance increases ... You should be able to recognise the graph of current against voltage for a diode. The diode has a very high resistance ...

But what do these three quantities really mean? A full explanation would take a whole semester, so let me instead give a brief summary. The ΔV is the change in voltage (also sometimes just called ...