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Created on: 30 July 2012
A LDR (Light Dependent Resistor) or photoresistor is a resistor that will change its resistance, depending on how much light is shining on it. As the light intensity on the LDR increases, so the resistance of the LDR decreases.
Schematic symbols for a LDR or photoresistor are shown below:
This photo shows what physical LDRs look like.