Circuit must be closed and there must be a source of p.d
What is current?
Flow of electrical charge?
How does the resistance change with current?
As current increases, electrons has more charge
When electrons flow through a resistor, they collide with atoms in the resistor - transfers energy to atoms, causing them to vibrate more which makes it more difficult for electrons to flow through the resistor
How does the resistance change with temperature?
Normal wires
Thermistor - hotter temperatures, resistance is low - often used in temperature detectors
How does the resistance change with length?
The greater the length, the more resistance and the lower the current
Electrons have to make their way through more resistor atoms - so harder than using shorter wire
How does the resistance change with light?
The greater the intensity of light, the lower the resistance - so resistance greatest when dark - used in automatic night lights
How does the resistance change with voltage?
Diode allows current to flow freely in one direction and in opposite direction, has very high resistance so no current can flow
