8.7 Types of Lighting: LED
8.7 Types of Lighting: LEDYou've probably heard the term LED—it stands for Light Emitting Diode. But what does that really mean?
Think of an LED as a tiny, super-efficient light maker. Unlike older bulbs that use filaments (like incandescents), gases (like fluorescents or HID lamps), or moving parts, an LED creates light using a special kind of solid material called a semiconductor. When electricity flows through this material, it directly produces light—no heat waste, no fragile parts, no warm-up time.
Why does this matter?
- Long-lasting: LEDs can last 25,000–50,000 hours (that's years of normal use!)
- Energy-saving: They use up to 90% less electricity than incandescent bulbs for the same brightness
- Durable: No glass filament or gas tube to break—great for outdoor lights, phones, cars, and more
- Instant on: Full brightness the moment you flip the switch
- Cooler operation: Less wasted heat means safer fixtures and lower cooling costs
In short: LEDs turn electricity straight into light—cleanly, efficiently, and reliably. That's why they're becoming the go-to choice for everything from nightlights to stadium lights.
LEDs do not directly produce white light. Due to this quirk, LEDs were originally used for colored light applications such as traffic lights and exit signs. LED lighting is very different from other lighting types such as incandescent and CFL. Key differences include:
- Light Source: LEDs are the size of a fleck of pepper, and can emit light in a range of colors. A mix of red, green, and blue LEDs is sometimes used to make white light.
- Direction: LEDs emit light in a specific direction, reducing the need for reflectors and diffusers that can trap light. This feature makes LEDs more efficient for many uses such as recessed downlights and task lighting. With other types of lighting, the light must be reflected to the desired direction and more than half of the light may never leave the fixture.
- Heat: LEDs emit very little heat. In comparison, incandescent bulbs release 90% of their energy as heat and CFLs release about 80% of their energy as heat.
Lifetime: LED lighting products typically last much longer than other lighting types. A good quality LED bulb can last 3 to 5 times longer than a CFL and 30 times longer than an incandescent bulb.
Source "LED-Lighting"- U.S. Department of Energy.
Text description of the LED Traffic Light image.
The image shows a traffic light against a backdrop of cloudy sky. The traffic light consists of three circular lights arranged vertically in a metal casing. Of these, the bottom light is illuminated green, signaling vehicles to proceed. The two upper lights are not lit. The green portion of the traffic light is made up of more than 90 individual LED lights.
Because of their extremely high efficiencies (150 lumens per watt!!, and up to 90 % more efficient than incandescent light bulbs), researchers found ways to convert their outputs to white light. As such, they are one of the highest efficiency lighting options available.
Here are three examples:
- Phosphor conversion, in which a phosphor is used on or near the LED to convert the colored light to white light
- Color-mixed systems, in which light from multiple monochromatic LEDs (e.g., red, green, and blue) is mixed, resulting in white light
- A hybrid method, which uses both phosphor-converted (PC) and monochromatic LEDs.
Methods of making white light from LEDs.
The image is a diagram titled "Creating White Light," showcasing three methods for generating white light using LEDs. Each method is illustrated with a schematic on a gray background.
- The first representation is labeled "Phosphor-Converted LED." It includes a large arrow labeled "White Light" pointing upward, under which a yellow layer labeled "Phosphors" converts the light from a magenta base labeled "Blue or UV LED."
- The middle section is labeled "Color-Mixed LED," displaying another upward-pointing arrow labeled "White Light." Below this, a block labeled "Color mixing optics" is overlaid on blue, green, and red squares labeled "Multi-colored LEDs."
- The third section named "Hybrid Method LED" also features an upward arrow indicating "White Light," above a similar "Color mixing optics" layer. Below it, alternating red and magenta squares are labeled "Colored and PC LEDs."
Beneath these diagrams, a gray panel holds descriptive text for each method:
- "PHOSPHOR-CONVERTED LED: Phosphors are used to convert blue or near-ultraviolet light from the LED into white light."
- "COLOR-MIXED LED: Mixing the proper amount of light from red, green, and blue LEDs yields white light."
- "HYBRID METHOD LED: A hybrid approach uses both phosphor-converted and discrete monochromatic LEDs."
These innovations have allowed these bulbs to be suitable for general lighting in residential applications. These bulbs last for 5-10 years depending on their usage. Now, you can find them in almost every store, and they look something like this.
Text description of the General Purpose LED Lights image.
The image features a row of five LED light bulbs positioned upright on a wooden surface. Each bulb emits a distinct color temperature, creating a gradient from warm to cool light. Starting from the left, the first bulb glows with a warm amber hue, the second with a neutral white light, the third with a cool white light, the fourth with a slightly cooler white, and the fifth with the coolest white light. The wooden surface has a natural, medium-brown color, providing a contrasting background to the bright whites of the bulbs.