View source for Light Dependent Resistor (LDR)

[[File:ORP12 LDR.jpg|300px|right]]
The resistance of [http://en.wikipedia.org/wiki/Photoresistor '''Light Dependent Resistors ''(LDR)'''''] decreases when light falls on them.

A typical example is the ORP 12 type which will vary its resistance from about 2 Megohms in the dark to 100 ohms in normal room lighting.

LDRs are frequently used as sensors in light activated '''[[Switches|switch]]''' circuits, for example, to switch on lights in the evening when it starts to get dark.