Photo resistors, also known as light dependent resistors (LDR), are light sensitive devices most often used to indicate the presence or absence of light, or to measure the light intensity. In the dark, their resistance is very high, sometimes up to 1MΩ, but when the LDR sensor is exposed to light, the resistance drops dramatically, even down to a few ohms, depending on the light intensity. LDRs have a sensitivity that varies with the wavelength of the light applied and are nonlinear devices. They are used in many applications but are sometimes made obsolete by other devices such as photo-diodes and photo-transistors. Some countries have banned LDRs made of lead or cadmium over environmental safety concerns.
- Operating Voltage: 5VDC
- Dimensions: 18 x 32 x 3 mm (L x W x H)
- Output type: Analog