The Sound of Science - "What's Up with All the Lightbulbs?"

Mar 1, 2019

J: I’m Jeremy Benson from NIU STEM Outreach and I’m in the studio with Kate Powers. This is the Sound of Science on WNIJ.

K: Hi Jeremy, I love the question you have from Gustavo today!

J: Gustavo just wants to know why lightbulb shopping has become so complicated in the past few years. Why does that question excite you so much Kate?

NIU STEM Outreach

K: When I moved into my apartment in August and turned on my kitchen overhead light, I noticed it was the kind of lighting you might expect in an operating theater. It was awful and blue and really bright. 

J: So, you went out and bought a new light bulb right away?

K: Um, if by right away you mean I avoided turning the light on for six months and just recently stopped by the hardware store to buy new lightbulbs, then yes. But seriously though, there are a lot of bulbs to choose from! All types of bulbs do the same basic thing: convert electrical energy into light energy. But how they do it differs.

J: I know the incandescent bulb works by heating the thin metal filament until it glows, right?

K: Right, and that is one of the reasons that the bulbs are so darn inefficient. More than 95 percent of the energy a traditional bulb uses is wasted as heat. Think about those tasty tiny cakes you used to bake with light bulb heat in your Easy Bake Oven when you were a kid. CFLs, or compact fluorescent lightbulbs, and LEDs, light emitting diodes, create light through luminescence. It's a more complicated process involving exciting electrons in atoms to create light.

J: That sounds about right, but why did we switch from CFLs to LEDs? 

K: Two main reasons for that. One is that LEDs are even more efficient than CFLs. And the second is the same reason why the lighting in my kitchen was awful -- the color of CFLs is hard to adjust. LEDs have very tunable light colors; you can easily adjust them for softer or brighter light.

J: Okay, that all makes sense. But what about all the new numbers on the box? I’m familiar with a 40 watt or 60 watt bulb, but those numbers have changed.

K: A watt measures how much energy a lightbulb uses, and the new lightbulbs use far less energy -- 3 W compared to 40 W!  With so many different levels of efficiency out there it is smarter to talk about lumens instead of watts. Lumens measure the brightness of light. A regular light bulb in your house is probably between 300 lumens to 1000 lumens. We just have to get used to thinking in lumens instead of watts.

J: That makes sense! Thanks for clarifying some of those lightbulb mysteries, Kate. Keep your questions coming to stemoutreach@niu.edu. This has been the Sound of Science on WNIJ.

K: Where you learn something new every day.