Photoconductors are materials whose electrical conductivity increases when exposed to light. They are also known as photoresistors or light-dependent resistors (LDRs).
How They Work:
- In darkness, photoconductors have high resistance due to few free charge carriers.
- When light shines on them, photons excite electrons, increasing the number of charge carriers.
- This lowers the resistance and allows more current to pass through.
Key Features:
- Passive devices (no amplification of signal)
- Respond to changes in light intensity
- Slower response time compared to photodiodes or phototransistors
Common Applications:
- Automatic night lights
- Light meters in cameras
- Solar street lamps
- Security systems
Photoconductors are simple, inexpensive tools for sensing light and are widely used in applications where speed is less critical but reliability and cost-effectiveness are important.