Made from high-resistance semiconductor materials like cadmium sulfide, this device allows more current to flow as incoming photons give bound electrons enough energy to jump into the conduction band. It is slow to react compared to a photodiode, making it unsuitable for data transmission. It is widely used in simple light-sensing circuits like automatic street lamps and night lights.
Just wire a photoresistor into the voltage divider to trigger the relay when the sun goes down.
Also heard as
- light-dependent resistor
- LDR
- photocell
Do not mix it up with
- Photodiode: A photoresistor changes its resistance based on light, while a photodiode acts as a current source.
Related terms
Photodiode
A semiconductor junction that converts light into an electrical current.
Resistor
A passive two-terminal component used to limit current flow, divide voltages, or terminate transmission lines.
Potentiometer
A three-terminal variable resistor used to manually adjust voltage or resistance in a circuit.