Photoresistor¶
A photoresistor or photocell is a light-controlled variable resistor. The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits photo conductivity.
A photoresistor can be applied in light-sensitive detector circuits and light-activated and dark-activated switching circuits acting as a resistance semiconductor. In the dark, a photoresistor can have a resistance as high as several megaohms (MΩ), while in the light, a photoresistor can have a resistance as low as a few hundred ohms.
Here is the electronic symbol of photoresistor.
Example
Lesson 9 Photo resistor (Mega Board Project)
Lesson 9 Photo resistor (R3 Board Project)
10. Light Alarm Clock (Scratch Project)