How LED Light Bulbs Work (2023)

How LED Light Bulbs Work (1)

The light bulb that has lit up our homes since the 1800s was officially on its way out after former President George W. Bush signed the Energy Independence and Security Act of 2007. Although the act didn't ban the use, purchase, sale or manufacture of incandescent bulbs, it did require household light bulbs to have 25 percent greater efficiency (which means 25 percent less energy use) than the traditional bulbs that used between 40 and 100 watts of electricity. The inefficient incandescent, where 90 percent of its energy is given off as heat, had fallen out of favor with the financially and ecologically concerned.

When the new lighting standards began in 2012, prime replacements for the incandescent light bulb were the higher-efficiency compact fluorescent lamps (CFL) and the light emitting diodes (LEDs). The CFL, though, has its own problems, primarily the inclusion of toxic mercury in the design and a strange, sometimes unpleasant color that even gives some people headaches.


Enter the LED lights. LEDs have been around for many years — they light up digital clocks, Christmas lights, flashlights, traffic signals, etc. But as far as household lighting goes, LEDs weren't taking off. Certain drawbacks had kept companies from manufacturing them in standard, replacement-size light bulb form. But in the last decade or so, these LED replacement bulbs, the kind you just screw into a lamp like you do an incandescent bulb, have become much more common — which is to say a large number of businesses and households are using them.

A 2017 survey showed that 70 percent of Americans had bought at least one LED light bulb and 38 percent had switched over from incandescent bulbs to LEDs. This percentage has likely increased since 2017.

In this article, we'll look into how LED light bulbs work, why they're a desirable lighting choice, and some of the pros and cons surrounding them. Let's begin with the basics: How does an LED produce light?



  1. LED Light Bulb Basics
  2. Advantages of LED Light Bulbs
  3. Concerns About LED Light Bulbs
(Video) How Modern Light Bulbs Work

LED Light Bulb Basics

An LED is what's called a "solid-state lighting" technology, or SSL. Basically, instead of emitting light from a vacuum (as in an incandescent bulb) or a gas (as in a CFL), an SSL emits light from a piece of solid matter. In the case of a traditional LED, that piece of matter is a semiconductor.

Stated very simply, an LED produces light when an electrical current passes through a microchip, which illuminates the tiny light sources called LEDs and the result is visible light. For a complete explanation, see How Light Emitting Diodes Work.


The problem with LEDs as primary home lighting was that while they emit a lot of light, the structure of an LED caused some of that light to get trapped inside. So, an LED bulb was traditionally dimmer than an incandescent bulb, and most people want their lamps and ceiling fixtures to be pretty bright.

Now, LEDs bulbs have brightened up. You can now find LED replacement bulbs that emit light equivalent to a 60-watt incandescent light bulb or higher, which makes them a viable technology for basic lighting needs at home. And a LED replacement light bulb has a life 24,000 hours longer than that of a traditional incandescent 60-watt bulb.

And it's cheaper. Replacing your home's five most frequently used light bulbs with LED ENERGY STAR models, can save you $75 a year.

Which brings us to the pros and cons of LED light bulbs.


(Video) What's Inside an LED Light Bulb

Advantages of LED Light Bulbs

How LED Light Bulbs Work (2)

First, there's the reduced energy use. The LED method of producing light uses far less energy to heat than do other lighting technologies. It's dramatically more efficient than the vacuum/filament method used in incandescent bulbs — using at least 75 percent less energy and it emits very little heat in comparison with incandescent bulbs (which release 90 percent of their energy as heat) and CFLs (which release about 80 percent of their energy as heat).

If you operate your lighting for 4,320 hours per year (360 hours per month/90 hours a week/12.85 hours a day), a 100-watt incandescent bulb would use 432 kilowatt-hours per year, while an equivalent 14-watt LED bulb would use just over 60 kilowatt-hours per year. LEDs also emit 90 percent less CO2 than the old halogens and 50 percent less than CFLs.

But energy efficiency is just part of the story. The other part is time efficiency: A good-quality LED bulb theoretically can have a life span of 25,000 hours or more, while incandescent bulbs have a 1,000-hour life span. Solid-state lights like LEDs are more stable light sources than incandescent or fluorescent bulbs, and the difference is startling: You'd have to leave a LED light on for 24 hours a day, seven days a week for three years before it matches an incandescent bulb's life span. (In fairness, not all LED light bulbs last as long as they can in theory. Some may have shorter life spans if parts wear out prematurely.)

Because of that time benefit, things get a bit more muddled when you get into the cost issue. A 60-watt LED replacement bulb runs in the area of $9.48 for a four-pack, while the same pack cost $3.97 for incandescent bulbs, according to Home Depot.

The reality is, even at $9.48 for a pack of four bulbs, LEDs will end up saving money in the long run, because you only need one every decade or two and you spend less money on home lighting, which can be six to seven times more energy efficient than incandescent lights and cut energy use by more than 80 percent.


(Video) How Do Light Bulbs Work? | Earth Lab

Concerns About LED Light Bulbs

LEDs are poised to take over household lighting. Philips has a collection of LED lights that includes color changes and Wi-Fi connected bulbs. And General Electric has a LED+ series that includes light bulbs with speakers, timers, color changes and more. It's estimated that LEDs will account for 75 percent of all lighting sales by 2030.

If you look at what the scientists are saying about LEDs, the picture does look pretty rosy. Breakthroughs are popping up at a breakneck pace. Except there's one problem.


A growing number of studies have come out about the blue light that LEDs emit. Researchers say it may be damaging our eyes and health. A French health agency said it can damage the eye's retina while disturbing our biological rhythm and sleep disruption. The agency recommended limiting the use of LED devices with the highest blue-light content, especially for children. This would include computers, smartphones and other screens, as well as perhaps, certain toys and decorative lights.

The 2019 report confirmed the agency's 2010 results regarding the toxicity of blue light to the eye, which can lead to failing eyesight. "They show short-term phototoxic effects associated with acute exposure and long-term effects associated with chronic exposure, which increase the risk of developing age-related macular degeneration (ARMD)," the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) wrote in its report.

For more information about LED light bulbs and related topics, look over the links on the next page.

Originally Published: Jul 23, 2009

LED Light Bulbs FAQs

How LED light bulbs work?

An LED produces light when electrons move around within its semiconductor structure. A semiconductor is made of a positively charged and a negatively charged component. The positive layer has "holes" -- openings for electrons; the negative layer has free electrons floating around in it. When an electric charge strikes the semiconductor, it activates the flow of electrons from the negative to the positive layer. Those excited electrons emit light as they flow into the positively charged holes.

What are the advantages of LED bulbs?

LED bulbs consume less power than other lighting technologies. They are also energy-efficient, safe to use and have a longer life. Compared to incandescent light sources, LED bulbs are 85% more energy efficient.

Can LED lights be left on all the time?

Yes, LED lights are ideal for places where light needs to be left on all the time. You don’t have to worry about high electricity bills because LED bulbs consume low power and generate less heat.

Do LED lights burn out?

Typically, LED lights can last for up to 25,000 hours. However, just like other electronic components, LED lights may burn out before that, due to extreme voltage fluctuations or premature part failures.

Does turning LED lights on and off shorten their life?

No, turning the LED light on and off doesn’t shorten its operating life. This usually happens with fluorescent bulbs. What really shortens the life of LED bulbs is overheating. So, make sure you don’t have electricity fluctuations to prevent overheating the LEDs.

(Video) How does an LED work at the molecular AND practical level? | Intermediate Electronics

(Video) How LED works ⚡ What is a LED (Light Emitting Diode)

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How does a LED light bulb work? ›

LED stands for light emitting diode. LED lighting products produce light up to 90% more efficiently than incandescent light bulbs. How do they work? An electrical current passes through a microchip, which illuminates the tiny light sources we call LEDs and the result is visible light.

What is LED short question answer? ›

LED stands for Light Emitting Diode. LED (light-emitting diode): The LED (light-emitting diode) is a PN junction device that emits light when a current pass through it in the forward direction, i.e. when LED is forward biased, it emits light.

What is LED explain long answer? ›

A Light Emitting Diode (LED) is a semiconductor device, which can emit light when an electric current passes through it. To do this, holes from p-type semiconductors recombine with electrons from n-type semiconductors to produce light.

How does it work light bulb? ›

Basically, an incandescent light bulb is a controlled fire on display. When electrical current makes contact with the base of the bulb, electricity enters and heats the tungsten filament housed inside. And when the filament heats up, “incandescence” is created, which is light produced by heat.

How do LED lights work physics? ›

Light-emitting diodes (LEDs) produce light (or infrared radiation) by the recombination of electrons and electron holes in a semiconductor, a process called "electroluminescence". The wavelength of the light produced depends on the energy band gap of the semiconductors used.

What actually causes the LED to light? ›

In a light emitting diode, the recombination of electrons and electron holes in a semiconductor produces light (be it infrared, visible or UV), a process called "electroluminescence". The wavelength of the light depends on the energy band gap of the semiconductors used.

What is LED one word answer? ›

LED stands for Light Emitting Diode. LEDs began as exciting but expensive electronic components in the sixties, used in handheld calculators and other similar devices.

How do LEDs help? ›

LEDs increase productivity and learning performance.

In addition, modern LED technology produces less heat and can help regulate facility temperature and lower lighting fixture count while reducing the need for overhead lighting.

What is an LED made of? ›

LEDs are comprised of compound semiconductor materials, which are made up of elements from group III and group V of the periodic table (these are known as III-V materials). Examples of III-V materials commonly used to make LEDs are gallium arsenide (GaAs) and gallium phosphide (GaP).

How a light bulb works step by step? ›

The incandescent light bulb consists of a thin tungsten filament inside of an inert gas-filled glass bulb. When electricity is applied across the filament, electrons begin to flow. These electrons encounter resistance from the tungsten material, and in turn produce energy as they collide. This energy turns into heat.

What makes a light bulb work and operate? ›

An incandescent bulb works on the principle of incandescence, a general term meaning light produced by heat. In an incandescent type of bulb, an electric current is passed through a thin metal filament, heating the filament until it glows and produces light.

How does an LED get its color? ›

LEDs produce different colors by using various materials which produce photons at different wavelengths. Those individual wavelengths appear as light of different colors. LEDs use materials that can handle the necessary levels of electricity, heat, and humidity.

Why do LED lights stay one color? ›

If your LED strips are stuck on one color when you change colors, it's probably because you have been pressing the same color button, which reaches peak value. Try using the reverse button to adjust it higher or lower. If still to no avail, check the contact of your pins and reconnect.

What is inside an LED light bulb? ›

It's called solid-state lighting because unlike incandescent and fluorescent lighting technologies, there are no gases involved in LEDs. Instead, energy is passed through a semiconductor (usually a solid chemical element or compound that can conduct electricity), lighting up the LED light bulb.

How is LED used in a sentence? ›

Led is the past tense of the verb lead: She led the party through the marshland. She lead the party through the marshland. The accident led to an astonishing discovery.

Where are LEDs used? ›

The high efficiency and directional nature of LEDs makes them ideal for many industrial uses. LEDs are increasingly common in street lights, parking garage lighting, walkway and other outdoor area lighting, refrigerated case lighting, modular lighting, and task lighting.

Why do LED bulbs glow when turned off? ›

So let's get rolling. Why Do LED Bulbs Glow When Off? An LED bulb, compared to halogen lamps or incandescent bulbs, has a much higher resistance on count of the integrated power supply unit. What happens is that the serial connection of the glow lamp clamps the circuit even when you turn the switch off.

Why is LED bulb good? ›

LED is highly energy efficient – Less heat, more light, lower cost. Use less electricity for the same light output - 85% less electricity when compared to conventional lighting and around 18% less electricity compared to CFL. Worldwide, around 20% of electricity is consumed in lighting.

Why are LED lights more efficient? ›

LEDs are the most efficient form of lighting

LEDs use much less energy to provide the same amount of light as other forms of lighting. One of the main reasons LEDs are so efficient is that most of their energy is used to solely create light, rather than creating light and heat, as less efficient forms of lighting do.

How much does LED lights save? ›

Lighting accounts for around 15% of an average home's electricity use, and the average household saves about $225 in energy costs per year by using LED lighting. if you are still using incandescent light bulbs, switching to energy-efficient lighting is one of the fastest ways to cut your energy bills.

Do LED bulb get hot? ›

Yes, new technology LED lighting can and will get hot, but when compared to the lighting of the past, temperatures are much safer. The heat from the lighting will also warm your surrounding environment but in comparison to old incandescent lighting, this ambient heat is greatly reduced when using LED lighting.

Is LED light natural or artificial? ›

Most artificial lights use electricity for energy, but some bulbs have a light bulb that changes the electrical energy. The production of visible light can happen in various ways, depending on the type of light bulb. Types of artificial lights include incandescent, fluorescent, vapor, and LED bulbs.

What are the 3 types of LED light bulbs? ›

Fundamentally, there are three different types of LED technology that are used in LED lighting – DIP, SMD and COB.

How does a bulb work Class 7? ›

An electric bulb works on the principle of hearing effect of current. It consists of a tungsten filament with a coating of thorium. This filament gets heated up to emit light when current passes through it.

What makes the bulb light up? ›

When a light bulb connects to an electrical power supply, an electrical current flows from one metal contact to the other. As the current travels through the wires and the filament, the filament heats up to the point where it begins to emit photons, which are small packets of visible light.

How does energy flow through a light bulb? ›

In the light bulb, the flow of charge through the filament heats it up and causes it to glow. In this way, the light bulb converts electrical energy to heat energy and light energy.

How is an LED different from a regular light bulb? ›

LEDs use much less energy than incandescent bulbs because diode light is much more efficient, power-wise, than filament light. LED bulbs use more than 75% less energy than incandescent lighting. At low power levels, the difference is even larger.

What makes LED lights change color? ›

The enemy of the LED's phosphor is the heat and UV radiation it emits during operation. Over time, these two forces degrade the phosphor and break down its components. The result is a fixture that used to give off nice white light but is now a little off—perhaps a bit blue or pink or green.

What are the disadvantages of LED? ›

  • High initial price: LEDs are currently more expensive (price per lumen) on an initial capital cost basis, than most conventional lighting technologies. ...
  • Temperature dependence: LED performance largely depends on the ambient temperature of the operating environment – or "thermal management" properties.
21 Sept 2015

Can you replace regular lights with LED? ›

Replacing your existing incandescent or halogen bulbs with durable LED bulbs offers numerous benefits. You enjoy an even better light performance and benefit from very low energy consumption. Furthermore, LEDs can handle all hues of white light, so the warm yellowish light of halogen bulbs is perfectly within reach!

Can you replace any bulb with LED? ›

Can You Put LED Bulbs in Halogen and Incandescent Fixtures? If everything fits and is the correct voltage, yes, you can easily swap all your halogen and incandescent bulbs in your fixtures with LED replacements.

How long do LED lights last? ›

The average lifespan of an LED is often rated up to 50,000 hours. This is about 50 times longer than a typical incandescent, 20-25 times longer than a typical halogen and 8-10 times longer than a typical CFL. If used 12 hours a day, an LED rated at 50,000 hours will last more than 11 years.

What is LED made out of? ›

The material used most often in LEDs is gallium arsenide, though there are many variations on this basic compound, such as aluminum gallium arsenide or aluminum gallium indium phosphide.

Why does a LED light turn white? ›

LEDs do not directly produce white light. There are two ways in which white light is produced from LEDs as below: Using a blue LED with a phosphor coating to convert blue light to white light by a process called fluorescence. Combining red, blue and green LEDs to produce white light.

Is there liquid in LED bulbs? ›

SWITCH uses liquid silicone to passively cool the LEDs. This means that the bulbs don't employ energy-consuming fans or pumps. The liquid in contact with the LEDs is heated, expanding and becoming more buoyant until it rises in contact with the cooler outer glass or plastic bulb shell.

Which gas is used in LED bulb? ›

A mixture of six inert gases (helium, neon, argon, krypton, xenon, and nitrogen) was introduced as the filling gas of LED bulb.

Do LED bulbs have liquid in them? ›

The bulb dome is filled with a nontoxic liquid that draws heat away from the LEDs housed inside. The liquid next to the LED chip gets warm, and then flows outward to the skin of the dome as it warms.

What fails in an LED bulb? ›

Unlike incandescent light bulbs, LEDs don't produce light using heat. This is part of what makes them so energy efficient. The downside is that their components can be sensitive to overheating, which can cause them to burn out prematurely.

Do LED lights take a lot of power? ›

LEDs Use Less Energy Than Traditional Lighting Sources

LEDs use between 25- and 80-percent less energy than incandescent lights. According to the DOE, the annual energy cost of a 60 W incandescent light is $4.80, but the comparable cost of a 12 W LED, providing the same light as a 60 W incandescent light, is $1.00.

What happens when LED fails? ›

The most common way for LEDs (and diode lasers) to fail is the gradual lowering of light output and loss of efficiency. Sudden failures, however rare, can occur as well. Early red LEDs were notable for their short lifetime.


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