**Learning Objectives**

- Recall the conditions for Ohm’s Law.
- Plot graphs for conductors that do not follow ohm’s law.
- Explain why a light bulb does not obey ohm’s law in terms of resistance…
- …and in terms of a collisions model.

**Key Questions**

- Why do some conductors not obey Ohm’s Law?
- How can we show that a bulb does not obey
Ohm’s Law?

**Key Words**

Voltage-current characteristic, graph, non-ohmic, gradient, resistance, thermistor, diode, bulb, LDR