Light-dependent Resistors
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Light-dependent Resistors
Light-dependent resistors, also known as photoresistors or LDRs, are electronic components that exhibit changes in resistance in response to changes in the intensity of light. They are passive components, meaning that they do not require an external power source to operate. LDRs are widely used in various applications, such as automatic lighting control systems, photographic light meters, and solar cells. The mechanism behind LDRs is based on the photoelectric effect, which is the emission of electrons from a material when it is exposed to light. In LDRs, the light energy causes the electrons in the semiconductor material to move from the valence band to the conduction band, leading to a decrease in the resistance of the device. The magnitude of the resistance change depends on the intensity of the incident light, with higher light intensity leading to a lower resistance. LDRs are made of semiconductor materials such as cadmium sulfide (CdS) or lead sulfide (PbS), which have a high resistance in the dark and a low resistance when exposed to light. The resistance of an LDR can range from a few hundred ohms in bright light to several megaohms in darkness. LDRs are available in different shapes and sizes, and their sensitivity to light can be adjusted by changing the material composition, the thickness of the semiconductor layer, or the surface area of the device. In summary, Light-dependent resistors are electronic components that exhibit changes in resistance in response to changes in the intensity of light. They are passive components that do not require an external power source to operate, and are widely used in various applications. The mechanism behind LDRs is based on the photoelectric effect, and they are made of semiconductor materials such as cadmium sulfide or lead sulfide. The resistance of an LDR can range from a few hundred ohms in bright light to several megaohms in darkness.
photoresistors, passive components, semiconductor materials, photoelectric effect, resistance change
CITATION : "Thomas Taylor. 'Light-dependent Resistors.' Design+Encyclopedia. https://design-encyclopedia.com/define/light-dependent-resistors?E=363513 (Accessed on October 14, 2026)"
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