I'm having some trouble understanding Ohm's law. My trouble is with the different ways it is described when referring to ohmic and non-ohmic conductors. If someone can answer this question I think it will clear up my doubts. (I made up this question myself — it's not homework!)
Which one of A and B is wrong, and why?:
A:
A non-ohmic conductor is one whose resistance changes with increasing
temperature, while an ohmic conductor is one whose resistance doesn't change
with increasing temperature.
B:
A non-ohmic conductor is one whose temperature changes with increasing
voltage, while an ohmic conductor is one whose temperature doesn't change
with increasing voltage.
Best Answer
Ohm's law assumes the temperature remains constant.
An Ohmic conductor is one in which the current flowing through it is proportional to the voltage applied across it.
A non-ohmic conductor is one in which the voltage and current are not linear.
A) The resistance of most conductors increases as the temperature increases, however being ohmic and not ohmic is not the reason.
B)What causes heating in a conductor is the current flowing through a conductor. The Power = current^2 * Resistance = voltage^2 / resistance
This power is converted into heat which increases the temperature as time goes on. The actual voltage does not matter as much as the how long it has been on the conductor.