- Led is the past tense of lead.
An example of led is someone who followed another somewhere.
Origin of LEDl(ight-)e(mitting) d(iode)
Origin of LEDl(ight-)e(mitting) d(iode).
- Simple past tense and past participle of lead.
led - Computer Definition
A semiconductor light source in the form of a transistor with a positive and a negative layer of particular semiconducting materials and a p-n (positive-negative) junction between them.The negative layer is doped with impurities to create extra electrons, which are negatively charged.The positive layer is doped to create extra holes into which electrons can migrate when a charge is applied, which has the effect of adding extra positive particles.When current is applied and the electrons move across the junction, from the n semiconductor layer to the p semiconductor layer, and settle into the holes, they release energy in the form of photons, i.e., light. (Note: A diode conducts current in only one direction, like a one-way gate.) The composition of the semiconductor material determines the color of light, how much of it is absorbed, and how much of it is released. LEDs manufactured with aluminum gallium arsenide (AIGaAs) are used in infrared (IR) applications such as fiber optics.Various other compounds, most including gallium (Ga), to create other colors in the visible and ultraviolet (UV) spectrum.Visible light-emitting diodes (VLEDs) operate in the visible light spectrum, and are found in clocks, watches, calculators, gauges, meters, and a wide variety of other devices.The infrared LEDs used in fiber optic transmission are, of course, much more sophisticated. LEDs pulse on and off relatively slowly, as specified by the cycle time, i.e., rise and fall times of signal intensity. Therefore, LEDs are relatively bandwidth-limited. LEDs also generate signals of relatively broad spectral width in the 850 nm region (850 Band), which wavelength attenuates substantially over relatively short distances. Slower LEDs emit light from an area etched into the surface of a semiconductor chip, while the faster LEDs emit light from the edge of the chip. The physical design of LEDs is such that they couple efficiently only to the relatively broad inner core of multimode fiber (MMF), and they do not tightly focus a collimated beam of light as does a laser diode. LEDs are used in local area networks (LANs), where they support transmission rates of up to 1 Gbps over relatively short distances. LEDs also are used in certain other short-haul transmission systems, including some passive optical networks (PONs). LEDs are relatively inexpensive and durable. See also 850 Band, coupling efficiency, cycle time, diode, IR, LAN, laser diode, MMF, PON, spectral width, transistor, UV, VCSEL, visible light, VLED, wavelength, and window.
(Light Emitting Diode) A display and lighting technology used in almost every electrical and electronic product on the market, from a tiny on/off light to digital readouts, flashlights, traffic lights and perimeter lighting. LEDs are also used as the light source in multimode fibers, optical mice and laser-class printers. See LED lightbulb. LEDs Vs. LCDs In the early 1970s, red LEDs were used in the first digital watches, but were superseded by lower-power LCDs within a few years. LEDs still use more power than LCDs, but less power than incandescent bulbs. They also last for decades and are virtually indestructible. LEDs and LCDs coexist on countless devices where the LEDs provide the status lights, and the LCDs display data. In addition, white or red, green and blue LEDs are used as the backlight source on many LCD TV sets. See LCD, LED TV and flat panel TV. Several Colors LEDs are semiconductor diodes that typically emit a single wavelength of light when charged with electricity. Originally red, today, several colors can be generated based on the material used for the tips of the probes. Aluminum indium gallium phosphide (AlInGaP) is used for red and yellow. Indium gallium nitride (InGaN) is used for green and blue, and with the addition of phosphor, for white light as well. See OLED, IRED, LED printer, fiber optics glossary and Nixie tube.
Variant of lead
transitive verbled, leading
- to show the way to, or direct the course of, by going before or along with; conduct; guide
- to show (the way) in this manner
- to mark the way for: lights to lead you there
- to guide, or cause to follow one, by physical contact, holding the hand, pulling a rope, etc.: to lead a horse by the bridle
- to conduct (water, steam, rope, etc.) in a certain direction, channel, or the like
- to guide or direct, as by persuasion or influence, to a course of action or thought: to lead pupils to think clearly
- to cause; prompt: trouble that led him to drink
- to be the head of; specif.,
- to proceed at the front of (a parade, etc.)
- to act as chief officer of; command the operations of (a military unit)
- to direct operations of (an expedition, etc.)
- to direct, conduct, or serve as the leader or conductor of (an orchestra, ballet, etc.)
- to be the first or foremost among; be at the head of: to lead one's class in grades
- to be ahead of by a specified margin
- to live; spend; pass: to lead a hard life
- to cause to live or spend: to lead someone a dog's life
- to aim a rifle, throw a ball, etc. just ahead of (a moving target or receiver)
- Card Games to begin the play with (a specified card or suit); lay down as the first card or suit of a hand or round
Origin of leadMiddle English leden ; from Old English lædan, causative of lithan, to travel, go, akin to German leiten: for Indo-European base see load
- to show the way by going before or along; act as guide
- to be led; submit to being led: said esp. of a horse
- to be or form a way (to, from, under, etc.); tend in a certain direction; go
- to come, or bring one, as a result: with to: one thing led to another, a cold can lead to pneumonia
- to be or go first; act as leader
- ☆ Boxing to aim a first blow or one designed to test an opponent's defense: to lead with a right jab
- Card Games to play the first card of a hand or round
- the part of director or leader; leadership: to take the lead in a project
- example: follow my lead
- first or front place; precedence: the horse in the lead
- the amount or distance that one is ahead: to hold a safe lead
- leash (sense )
- anything that leads or serves as a clue
- information that directs a salesperson to a potential customer, a source of new business, etc.
- a long, narrow, navigable passage in an ice pack or ice field
- the most important news story, as in a newspaper or telecast
- the opening words or paragraph of a news story, containing all the essential facts of the story
- ☆ Baseball a position taken by a base runner a short distance from his or her base in the direction of the next
- ☆ Boxing the act of leading, or the blow used
- Card Games the act or right of playing first, as in a hand, or the card or suit played
- Elec. a wire carrying current between two points in a circuit, between devices, etc.
- ☆ Mining a stratum of ore; lode, ledge, or vein
- Music the leading part or main melody in a harmonic composition
- Naut. the course of a rope
- the principal role, or a main role, in a play or other production
- the actor or actress who plays such a role
- to begin; start
- ☆ Baseball to be the first batter in the lineup or of an inning (sense )
- to conduct further
- to lure or tempt
lead someone a merry chase
lead up to
- to prepare the way for
- to approach (a subject) in a subtle or indirect way
lead with one's chin