This photocell, light dependant resistor sensor changes its resistance depending on the light it is exposed to enabling it to act as a light sensor. Works in the visible spectrum so you can detect when a light is turned on or if it is getting dark outside.
Our Code: SEN-10080
Supplier Link: [SparkFun MPN:9088]
This light dependant resistor also goes by other names like a photocell, photodetector, photo resistor, CdS or photoconductive cell. That's a lot of names for one little simple device.
With only two leads it is simple to use. Keep it in the dark and its resistance is 10k Ohms. Shine a light on it and the resistance is 1K Ohm. Anywhere in between and it will tell you approximately how much light is about. Hook it up to an analog input pin and read the light levels.
The devices has a rating of 150V and 100mW so it is suitable for all kinds of analogue circuits as well such as switching on lighting when it gets dark via a relay and some transistors.