Light-operated switch. The electronic components making up this switch circuit are seen in the plastic holder (white),with wires completing the circuit. The key component is the light-dependent resistor (LDR),which is the component in the upper left corner of the plastic holder. The other components include resistors,a lamp (right),and the power source (batteries,upper left). This is a 6-volt power source,and the circuit operates as a potential divider (dividing the potential voltage from the power source). A circuit like this can be used to detect either an increase or decrease in light,depending on the arrangement,and switch another device on or off,such as a light-sensitive alarm or a street light |