Resistance falls as light rises. Put one in a divider with a 10 kOhm resistor and you have a light sensor on any analog pin - the foundation of every automatic-nightlight project ever built.
Specifications
| Light resistance (10 lux) | 8-20 kOhm |
| Dark resistance | 1 MOhm |
| Peak wavelength | 540 nm |
| Response time | 20 ms rise / 30 ms fall |
| Pack size | 10 pieces |