Description: This is a very small light sensor. A photocell changes (also called a photodetector, photo resistor, CdS or photoconductive cell) resistance depending on the amount of light it is exposed to. These little sensors make great ambient light triggers (when light in the room turns on, do something).
Based on 3 ratings:
Using it with an arduino uno for measuring ambient light level. Works great.
Used with a 10K fixed resistor in a voltage divider and it provides a very good dynamic range through a normal room lighting range.