INDEX

LIGHT SENSORS
Light sensors are used to measure the intensity of light. Mostly available sensors are Cadmium Sulphide LDR sensor, IR senor like photo diode,photo transistor, TSOP1738. For beginners LDR is easy to handle. So as a beginner better start with LED+LDR combination or IR LED+photo diode . LDR is economical than other sensors and easy to handle.
LIGHT DEPENDENT RESISTOR(LDR):
LDR is basically a resistor whose resistance varies with intensity of light. More intensity less its resistance (i.e, in black it offers high resistance and in white it offers less resistance). This is the basic sensor which beginners should start with, which is having cost less than Rs.6.Figure below show some of the pictures of LDR which i obtained from some site.

Fig.1 shows LDR's with greater surface area, Fig.2 shows the LDR's which are available about Rs.5, which is commonly used. Greater surface area,better the sensing will be. The sensing material is made of Cadmium Sulphide.