Seasonal Spectroscopy

Season’s greetings from PASCO scientific. This is Tom Loschiavo, Chemistry Education
Manager at PASCO, and today we wanted to have some fun with
some holiday lights. So we have some LEDs, some traditional incandescent
bulbs, and some white LEDs. And we wanted to investigate them using a
spectrometer and our SPARKvue software. So let’s take a look. First we’ll look at a traditional incandescent
bulb. One thing to note about them is they do get
warmer than the other ones, and compared to the white they look a little
bit more yellow. Let’s see why. We’ll start our spectrometer. On the software I’m running intensity versus
wavelength. And we’ll just take a look at this incandescent
bulb. Notice it’s a very broad spectrum going all
the way from blue over to red and into infrared, and it’s actually a very bright bulb. Now let’s look at the LEDs. First we’ll look at a white LED to do a comparison. So here is a white LED. We’ll use the spectrometer again with the
fiber optic cable. And there we go. Not the same broad spectrum. Sort of a peak in the blue area and then another
peak in the yellow-green area, giving a different color signature than the
incandescent bulb. We can also look at the colored LEDs. First let’s take a look at red. We’ll start a new run. It’s also a very bright bulb, and it is very
much in the red part of the spectrum. We can also look at blue. We’ll start another run for the blue. An interesting thing about the blue is if
you look at the peak of the white LED, there’s a lot of blue in it. This blue is also fitting into that same profile
on the spectrum. And we’ll take a look at the yellow and the
green also. So here’s a yellow LED. It’s noticeably not as intense and very much
in the yellow-orange part of the spectrum, as you would expect. And finally a green LED. Also not very intense and also very much in
the yellow part of the spectrum. These two bulbs might be very similar. So we’re just having a little fun with some
holiday lighting. I want to wish everyone out there a happy
holiday and happy experimenting in 2013. Thanks from PASCO.


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