While there are numerous types of electronic component, only photoelectric devices used intensity of light for their functionality. There are four main types of photoelectric devices each with their own specific purpose. Photomultiplier Tube. A photomultiplier tube or PMT, is a photoelectric device that is an extremely sensitive detector of visible, infrared and UV light. Photodiodes have largely replaced PMTs, however, the high gain and frequency response that results from the high sensitivity makes PMTs very useful in physics, astronomy and medical imaging. Light-dependent resistor. Light-Dependent Resistors (LDRs) are also referred to as photoresistors, or photoconductors. Its resistance, or opposition of the passage of an electric current, decreases with increasing intensity of light. If light falling on the device is a high enough frequency, enough energy is present to pass an electrical current. Inexpensive cadmium sulfide cells are used in consumer electronics such as clock radios, security alarms, camera light meters and street light. More sophisticated cells that detect infrared frequencies are used in astronomy and spectroscopy. Photodiode. Photodiodes function as photodetectors in a number of devices. The photodiode is packaged with a window that lets light into the sensitive part of the device. The photodiode can also be constructed without a window to detect UV light and X-rays. They are used in consumer electronics including smoke detectors, and receivers for remote controls for TVs and DVD players. Photodiodes are also used in science to accurately measure light intensity. Photovoltaic Cell. Photovoltaic cells or solar cells are a familiar device used in calculators, satellites, and water pumping devices. The cell converts solar light which is in the form of protons, into electricity. Solar cells can also convert energy from non-solar sources light incandescent light bulbs. Angela Oliver is an author for HRent.com. H and R Enterprises specializes in the wholesale distribution of electronic components, including various types of resistors and diodes.