MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
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.
Model release not required. Property release not required.