LDR Stands for Light Dependent Resistor and its Resistivity varies with Incident Electromagnetic Radiations, Other names of LDR are photoresistor, Photoconductor, Photocell, and photo conducting cell. LDR is made of Semiconductor materials like Silicon and Germanium which have high Resistance. It is a light-sensitive device, so this resistor has a different resistance value in the day and different vale at night. it has Two Cadmium Sulphide (CDs) PhotoConductive Cells with spectral responses which are similar to that of the human eye. Cell resistance falls with increasing light intensity.
- Daylight: 5000Ω
- Dark: 20000000Ω
LDR 5mm changes resistance with the change in the ambient light exposure on the surface of the sensor. whenever you need a way to sense the level of ambient light, there is no easier way to do it other than using the LDR sensor as when the light on the sensor increases, then the resistance across both the two leads decreases respectively.