A photoresistor or light dependent resistor or cadmium sulfide (CdS) cell's a resistor whose resistance decreases with increasing incident light intensity. It can also be referenced as a photoconductor. A photoresistor's made of a high resistance semiconductor. If light falling on the device's of high enough frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electron (and its hole partner) conduct electricity,… (More on Photoresistor)