Fritzing Creator Kit - #11 Automatic Lighting System
A light dependent resistor (LDR) or photoresistor is made of a material that changes its resistance in proportion to the intensity of the light it is exposed to. The more light that falls on it, the lower the resistance. In our example, we will take advantage of this capability to automatically turn on the headlights of a car.
The photoresistor leads are very long. Make sure that there is no contact between them.