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PHOTO MULTIPLIER
Photomultiplier tubes (photomultipliers or PMTs for short), members of the class of vacuum tubes, and more specifically phototubes, are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum
COMBINING TWO SCIENTIFIC DISCOVERIES:
 Photoelectric effect
 Secondary emission
APPLICATIONS
 Interruptions in beams of light.
 Detect nuclear and particle radiation in physics experiments.
 Research laboratories to measure the intensity and spectrum of light-emitting materials.
 Blood analysis devices used by clinical medical laboratories.
PHOTO RESISTOR
A photo resistor or light dependent resistor or cadmium sulfide (CdS) cell is a resistor whose resistance decreases with increasing incident light intensity. It can also be referred to as a photoconductor.
applications
 camera light meters, street lights, clock radios, alarms, and outdoor clocks.
 They are also used in light emitting diode to control gain reduction.
 PbS and InSb LDRs are used for infrared astronomy and infrared spectroscopy.
 Photoresistors are used for changing energy types
PHOTO VOLTAIC CELL
Photovoltaics (PVs) are arrays of cells containing a solar photovoltaic material that converts solar radiation into current electricity. Materials presently used for photovoltaic include monocrystalline silicon, polycrystalline silicon, microcrystalline silicon.
LIQUID CRYSTAL DISPLAY
A liquid crystal display (LCD) is a thin, flat electronic visual display that uses the light modulating properties of liquid crystals.
LIGHT EMITTING DIODE
A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices, and are increasingly used for lighting. Introduced as a practical electronic component in 1962