L.E.D. Light Emitting Diode
Definition
An LED (Light Emitting Diode) is a semiconductor device that emits light when current flows through it. LEDs are used in many different applications, including lighting, displays, and sensors.
LEDs work by using the principle of electroluminescence. Electroluminescence is the emission of light by a material when an electric current is passed through it. In LEDs, the light is emitted by a semiconductor material called gallium arsenide phosphide (GaAsP).
The colour of the light emitted by an LED is determined by the energy gap of the semiconductor material. The energy gap is the difference in energy between the valence band and the conduction band of the semiconductor material. The higher the energy gap, the shorter the wavelength of the light emitted.
LEDs are becoming increasingly popular because they are more efficient and longer-lasting than traditional light bulbs. LEDs also produce less heat, which makes them safer to use.
How can the word be used?
Displays: LEDs are used in displays, such as digital clocks and billboards.
Different forms of the word
Noun: LED is a semiconductor light source that emits light when current flows through it.
Adjective: LED is an adjective that describes something that is related to LEDs. For example, an LED light is a light that is made with LEDs.
Verb: To LED is to light with LEDs. For example, to LED a sign is to light a sign with LEDs.
Etymology
The word "LED" is an acronym for "Light Emitting Diode". It is a semiconductor device that emits light when current flows through it.
The word "LED" was first used in the 1960s. It is a combination of the words "light" and "diode".
The word "diode" comes from the Greek word "diōdēs", which means "two-way". This is because a diode is a device that allows current to flow in one direction only.
The word "light" comes from the Old English word "leoht", which also means "light".
So, the word "LED" literally means "light-emitting diode".
Question
What is an LED?
AQA Science Exam Question and Answer
Question:
Describe the working principle and advantages of Light Emitting Diodes (LEDs). Explain how LEDs are more energy-efficient compared to traditional incandescent and fluorescent lights. Provide examples to support your explanation.
Answer:
Light Emitting Diodes (LEDs) are semiconductor devices that emit light when an electric current passes through them. The working principle behind LEDs involves the movement of electrons in a semiconductor material, which releases energy in the form of photons, creating visible light. LEDs offer several advantages over traditional incandescent and fluorescent lights.
Firstly, LEDs are highly energy-efficient. Unlike incandescent bulbs that generate light by heating a filament, LEDs directly convert electricity into light, minimizing energy wastage as heat. This efficiency results in significant energy savings and reduced electricity bills. For instance, an LED bulb uses about 80% less energy compared to an incandescent bulb producing the same amount of light.
Secondly, LEDs have a longer lifespan. Traditional bulbs tend to burn out relatively quickly due to the filament's degradation, while LEDs can last tens of thousands of hours before dimming. This longevity further contributes to reduced maintenance costs.
Moreover, LEDs are directional light sources, emitting light in a specific direction, which reduces the need for reflectors or diffusers to redirect the light. This feature is particularly useful for applications like spotlights or automotive headlights.
In contrast, incandescent bulbs and fluorescent lights waste energy as heat, have shorter lifespans and often contain hazardous materials like mercury. LEDs' efficiency, longevity, and eco-friendliness make them a superior choice for various lighting needs, from residential to industrial settings, showcasing their significant advantages over traditional lighting technologies.