1) Resistive component 
A photoresistor or light-dependent resistor (LDR) or photocell is a light-controlled variable resistor. The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits photoconductivity. A photoresistor can be applied in light-sensitive detector circuits, and light- and dark-activated switching cir...
semiconductor photosensitive device that utilizes the change of electric conductivity produced by the absorption of optical radiationphotoelectric device that utilizes the change of electrical conductivity produced by the absorption of optical radiation