The led emits visible light when its

Light Emitting Diode (LED) What is light? Before going into how LED works, let’s first take a brief look at light self. Since ancient times man has obtained light from various sources like sunrays, candles and lamps. In 1879, Thomas Edison invented the incandescent light bulb. In the light bulb, an electric current is passed through a filament inside the bulb. When sufficient current is passed through the filament, it gets heated up and emits light. The light emitted by the filament is the result of electrical energy converted into heat energy which in turn changes into light energy. Unlike the light bulb in which electrical energy first converts into heat energy, the electrical energy can also be directly converted into light energy. In Light Emitting Diodes (LEDs), electrical energy flowing through it is directly converted into light energy. Light is a type of Photons have energy and momentum but no mass. Atoms are the basic building blocks of matter. Every object in the universe is made up of atoms. Atoms are made up of small particles such as electrons, protons and neutrons. Electrons are negatively charged, protons are positively charged, and neutrons have no charge. The attractive force between the protons and neutrons makes them stick together to form nucleus. Neutrons have no charge. Hence, the overall charge of the nucleus is positive. The negatively charged electrons always revolve around the positively charged nucleus because of the electrostatic force of attrac...

I have recently purchased an IKEA LED bulb with G9 fittings, to replace a halogen one. The bulb is installed in a lamp with 3 other halogen G9s in a 3 + 1 configuration with a 3-state switch. "up" lights up all four bulbs, "down" lights up only the socket where the LED is. I have found a strange behaviour. When the lamp's switch is in the off position, the LED bulb still emits a very dim light, whereas the halogen ones do not. What is happenning here? Is this normal? From my limited knowledge I would guess the lamp's circuit has some residual current which is not enough to light up the halogen bulbs, but makes the LED emit the dim light observed. \$\begingroup\$ When you say it continues to glow, does it glow continuously, or just for seconds/minutes? If the latter, what you are seeing is the phosphors continuing to glow. Most "white" LEDs are actually blue/violet/UV LEDs exciting phosphors to produce white light. When the LEDs turn off, the phosphors continue to glow off a little while. No additional energy is being consumed. \$\endgroup\$ There are two possibilities the switch is inserted: • Switch switching the voltage line. • Switch switching the GND line. The capacitors shown in the circuit are the capacities the (more or less) long lines form to GND. If the 2nd circuit is what you have the lamp always is connected to alternating voltage. In that case there is a possibility of some very low alternating current flowing via C10 to GND even if the switch is open. You can...

LED, in full light-emitting diode, in The familiar The term diode refers to the twin-terminal structure of the light-emitting device. In a flashlight, for example, a wire filament is connected to a n-type, semiconductor) the charge carriers are electrons, and in the other (the positive, or p-type, semiconductor) the charge carriers are “holes” created by the absence of electrons. Under the influence of an p- n junction, providing the electronic excitation that causes the material to luminesce. In a typical LED structure, the clear epoxy dome serves as a structural element to hold the lead frame together, as a lens to focus the light, and as a p- n-type GaP:N layers represent nitrogen added to gallium phosphide to give green emission; the p- n-type GaAsP:N layers represent nitrogen added to gallium arsenide phosphide to give orange and yellow emission; and the p-type GaP:Zn,O layer represents zinc and oxygen added to gallium phosphide to give red emission. Two further enhancements, developed in the 1990s, are LEDs based on aluminum gallium indium phosphide, which emit light efficiently from green to red-orange, and also blue-emitting LEDs based on

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The light emitting diode is the most visible type of semiconductor diode. They emit a fairly narrow bandwidth of either visible light at different coloured wavelengths, invisible infra-red light for remote controls or laser type light when a forward current is passed through them. The “ Light Emitting Diode” or LED as it is more commonly called, is basically just a specialised type of diode as they have very similar electrical characteristics to a PN junction diode. This means that an LED will pass current in its forward direction but block the flow of current in the reverse direction. Light emitting diodes are made from a very thin layer of fairly heavily doped semiconductor material and depending on the semiconductor material used and the amount of doping, when forward biased an LED will emit a coloured light at a particular spectral wavelength. When the diode is forward biased, electrons from the semiconductors conduction band recombine with holes from the valence band releasing sufficient energy to produce photons which emit a monochromatic (single colour) of light. Because of this thin layer a reasonable number of these photons can leave the junction and radiate away producing a coloured light output. LED Construction Then we can say that when operated in a forward biased direction Light Emitting Diodes are semiconductor devices that convert electrical energy into light energy. The construction of a Light Emitting Diode is very different from that of a normal signal d...