This photoresistor changes its resistance in the presence of light. The resistance varies between 500K in full dark to 10K in bright light. The peak spectral response is between 550nm and 650nm. It can be used to measure light/dark or the relative brightness of light sources. It is extremely easy to interface to the analog input pins on an Arduino, Netduino or other microcontroller (PIC, AVR, etc.), as well as an easy device to use in analog circuits.
Dimensions: 5mm x 4mm, with 30mm long leads.
Photoresistors are also known as "CDS Cells" or "LDRs" (Light Dependent Resistors).
This is a must-have part for any hobbyist or young electronics enthusiast. Its great for classroom electronics demonstrations and science fairs. This is the sensor at the heart of dusk-to-dawn sensors, automatic headlights, etc.
For full specs, please see the DATASHEET.