10/03/2025 5:30 am
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I am new to electronics and trying to understand how a Light Dependent Resistor (LDR) works. I know its resistance changes with light, but how does this actually work at a deep level? How does this behavior affect circuits that use LDRs? Also, in what types of projects or devices are LDRs commonly used?
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11/03/2025 10:23 am
A Light Dependent Resistor (LDR), or photoresistor, is a passive component that changes its resistance based on light intensity. It is made of a semiconductor material like cadmium sulfide (CdS), which exhibits photoconductivity—its resistance decreases as light exposure increases.
In darkness, the resistance is high (megaohm range), while it drops significantly (to hundreds of ohms) in bright light. This property makes LDRs useful in applications such as automatic lighting, light meters, and alarm systems.
They are commonly used in voltage divider circuits to provide a variable output voltage that microcontrollers or analog circuits can read.
