Monday, May 2, 2016

How do light bulbs work?

Light bulbs come in a dizzying array of shapes and technologies, but have you ever wondered just how they work?

All light bulbs consist of at least two simple parts:
·         A base to attach to an electrical socket
·         A glass bulb

But depending on the technology, the similarities stop there.

In incandescent bulbs, electricity flows into a bulb that contains argon gas. A tungsten filament heats up until it starts to glow. Over time, this heat (up to 4600 degrees!) causes the filament to break, thus burning out the bulb. That’s why incandescents are notoriously short-lived and inefficient and why most are not being sold in the U.S. anymore.

Halogen bulbs are really enhanced incandescents. The filament is the same, but the gas is at a higher pressure, which means the glass bulb is made of stronger material to withstand the added pressure. Used for task lighting that requires bright light, halogens offer a compact design, but they are very hot and are slowly being replaced by LEDs. 

With CFL bulbs, electricity passes through a low-pressure tube containing argon and a small amount of mercury vapor. The result is an invisible ultraviolet light that excites a fluorescent coating on the inside of the tube, which then emits visible light. CFLs take longer to reach full lighting potential and take a little more energy to get going, but once they’re on, they use 70% less energy than an incandescent.

LED bulbs use solid-state lighting technology (SSL), which causes light to emerge from a semiconductor.
When electrons move around in the semiconductor, light is the result.

What about that gas?

The gas inside a bulb also varies. With the exception of LEDs, all bulbs contain a gas under various amounts of pressure. What’s important to know?
·         Helium, neon, argon, and krypton are typically used in decorative lighting. They produce a clean, white light and more lumens (brightness) at lower wattages. A 60-watt bulb with these gases will typically last for about 3,000 hours.
·         Xenon is used for flash tubes, typically used in cameras, and is generally more expensive. However, it’s the best gas for extending filament life. It gives off a whiter light than other bulbs of the same wattage.
·         Krypton also helps increase filament life and makes smaller bulbs more efficient.

And if that isn’t confusing enough, combinations of gases are used in some bulbs.


As you can see, choosing the right bulb isn’t as easy as it used to be. Here are a few bulbs that look similar but contain different gases.

Krypton bulb
(item JCV120V60WGSN)
Xenon bulb
(item KX40/CL/E12)

Halogen bulb
(ESN)




Remember, we’re always here to help when you need advice for finding the perfect bulb!


Our customer service reps are always on hand to answer your questions! Call us at Bulb Direct (800-772-5267).