A photoresistor or photocell is a light-controlled variable resistor. The resistance of a photoresistor decreases with increasing incident light intensity. A photoresistor can be applied in light-sensitive detector circuits, and light- and dark-activated switching circuits. It's also called light-dependent resistor (LDR).
A phototube or photoelectric cell is a type of gas-filled or vacuum tube that is sensitive to light. Such a tube is more correctly called a 'photoemissive cell' to distinguish it from photovoltaic or photoconductive cells. Phototubes were previously more widely used but are now replaced in many applications by solid state photodetectors.
The resistance of a photoresistor decreases with increasing incident light intensity. A photoresistor can be applied in light-sensitive detector circuits, and light- and dark-activated switching circuits. It's also called light-dependent resistor (LDR). In this tutorial you will learn how to use a photoresistor with and without arduino uno.
Photocell is also called an electron tube, photoelectric cell, electric eye, and phototube. This is an electronic instrument that is very vulnerable to incident radiation mainly light that is utilized for the generation or regulating the output levels of electric current.
Hence these Photoresistors are also known as photoconductive cells or just photocell. The idea of Photoresistor developed when photoconductivity in Selenium was discovered by Willoughby Smith in 1873. Many variants of the photoconductive devices were then made.
The first such sensor was the “phototube” or “photo-electric cell” (Fig 1A) which consists of a photo-sensitive cathode in a vacuum (or, sometimes, very low-pressure gas) tube which when illuminated emits electrons which move to a positively biased anode, allowing a current to flow which is proportional to the light intensity.
Photoresistor In a Nutshell " Photons " + " Resistor " = Photoresistor : A special type of variable resistor whose resistance depends on the intensity of light falling on it. Other Names: Photoconductor, Photocell, Light dependent resistor(LDR)