What is (Light dependent resistor) (LDR)

Light Dependent Resistor (LDR) is a type of resistor. Whose resistance changes with the amount of light falling on it. Also known as a photoresistor, an LDR's resistance decreases as the light intensity increases, and vice versa.

The function of an LDR is based on its semiconductor material, which exhibits a photoconductivity property. When exposed to light, the energy from photons in the light causes the semiconductor material electrons to move thus lowering the resistance of the LDR. This characteristic makes LDRs useful in various applications, such as light-sensitive switches, photographic exposure meters, and automatic street lights, where they can be employed to detect ambient light levels and adjust electronic circuits accordingly.