The ohm law for electricity is given by R = V/I Yesterday, my friend just took an experiment report to me which show the relation between R, V and I on a resistor and semiconductor separately. I saw that for resistor, R is almost a constant so V vs I is a straight line. However, for semiconductor, R is no longer a constant. My question is if I get a table to show a relation of V and I for a semiconductor, can I still apply R=V/I to calculate the resistance for difference I and V? What I am really confusing is in some textbook, it said the ohm law is R=V/I which gives a linear relation b/w V and I. So does it mean even I can use the same formular to calculate R but since it is no longer a linear relation, it is no longer the ohm law?