PhysicsCode 9702
Resistance and resistivity
What this topic asks you to be able to do
- define resistance
- recall and apply V = IR
- sketch the I–V characteristic for each of: a filament lamp, a semiconductor diode, and a metal conductor whose temperature stays constant
- account for a filament lamp's resistance going up as the current rises, since its temperature also goes up
- state Ohm’s law
- recall and apply R = ρL/A
- understand that a light-dependent resistor (LDR) has a resistance that falls as light intensity rises
- understand that a thermistor's resistance drops as its temperature rises (it is assumed that thermistors possess a negative temperature coefficient)