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Let's start at the beginning



Hasta la vista, halogen

Extra hardware


See ya, CFL

Consider the LED

Later, LED

Lights out

There's a lot of science at work inside of your light bulbs, but if you want to take a closer look at how they work, you'll need to find a way inside.

Oh, look. A hammer!

Caption by / Photo by Chris Monroe/CNET

Our first bulb is the humble imcandescent, an age-old light source invented by Thomas Edison and still used throughout the world today.

Caption by / Photo by Tyler Lizenby/CNET

Inside, you'll find a tungsten filament suspended between two spires. Electricity travels up one spire, across the filament, and down the other spire. In the process, the filament heats up, glows, and emits light.

Incandescents work because tungsten is an incredibly durable chemical element with a melting point that's about as high as it gets. It can handle the heat, but it doesn't make for a very efficient light bulb, because all of that heat is really just wasted energy.

Caption by / Photo by Tyler Lizenby/CNET

This brings us to halogens, which are essentially the same thing as incandescents, but with an extra trick.

Caption by / Photo by Martin LaMonica/CNET

Let's take a look inside!

Caption by / Photo by Tyler Lizenby/CNET

As you can see, there's still a filament here, but it's encased in a little chamber. That chamber also contains halogen gases like bromine and iodine -- their job is to essentially recycle some of the evaporated tungsten back onto the filament after it burns off so that it can be used again. This extends the life of the bulb, and also helps it put out more light using less energy.

Caption by / Photo by Ry Crist/CNET

Up next, compact fluorescent light bulbs, or CFLs. You might have a few of these in your home -- ever wonder what happens when you hit one with a hammer?

Caption by / Photo by Tyler Lizenby/CNET

For starters, you get a cool GIF like this one. You'll also see a little puff of gasses escaping -- those are the bulb's namesake fluorescent gasses. They include neon, argon, and mercury vapor, which gives off light when you pass electricity through it. Mercury is pretty toxic, so if you break one, you'll want to be pretty careful about how you clean it up.

Caption by / Photo by Tyler Lizenby/CNET

If mercury isn't your thing, then consider an LED. It's an even more efficient lighting option, and it's totally mercury-free. But how does it work?

Caption by / Photo by Tyler Lizenby/CNET

It's all in the name. "LED" stands for "light-emitting diode," and inside, you'll find a bunch of them. Each one is a tiny junction with two nodes. When electricity passes through, it jumps from one node to the other and gives off light in a process called electroluminescence.

Caption by / Photo by Tyler Lizenby/CNET

LEDs also promise to last years or even decades, which makes it more important than ever to buy the right bulbs for your home. That's why we test and review the latest light bulbs (and why, on occasion, we smash them, too).

Caption by / Photo by Chris Monroe/CNET
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