Apologia Science Curriculum – It Glows!
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Getting Started
It’s not often that you find a cool science experiment that introduces you to a fun new way to surprise your friends. With this science project, you’ll learn a little bit about ultraviolet rays – and a lot more about fun ways to play with household materials. No matter where you are in your Apologia science curriculum, take a moment or two to play around with this fun experiment. After all, any chance you get to have fun can only enhance your overall Apologia science curriculum, right?
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A terrific resource to get your science questions answered is the homeschool science project blog. Great experiments too!
Materials and Steps
To get started, you’ll need just a few materials:
• A black light
• Petroleum jelly (such as Vaseline)
• A piece of paper
Once you’ve gathered these materials together, it’s time to get started with the experiment. Here are the steps you’ll need to take:
• Make invisible ink. Confused? Don’t be! Take a look at your materials and try to guess which one of them could be the invisible ink. If you guessed petroleum jelly, you’re right! Dip your finger into the jelly and write a message on the piece of paper.
• Turn off the lights in the room.
• Turn on the black light.
• Record your observations.
• Now, glance down at the finger you used to write the message. Record your observations.
What Happened?
As you’ve probably noticed, the petroleum jelly seems to glow under the black light. Anything coated with petroleum jelly, whether it’s your finger or your message on the piece of paper, glows when the black light hits it. But why?
Let’s shed some light on it:
The black light that you used is a special kind of light. Black lights emit a very low frequency of light, so our eyes can barely see anything in it. It’s almost like invisible light. This type of light is called ultraviolet light because our eyes cannot detect all of it.
Want to learn more about light and the physics behind it? Check out this website for great homeschool science resources. It’s definitely one worth bookmarking for tons of great ideas for your Apologia science curriculum.
There are several different kinds of ultraviolet light. UV-B light has a high energy. UV-B light is the type of light that gives us sunburn. However, UV-A light, such as the black light you used, will not give you sunburn, but it does have a lower frequency of energy.
The Big Idea
Now for the big question: if we are unable to see UV-A light, why does the petroleum jelly glow when the light hits it? Good question.
Remember that the light we see is only a reflection from the surface of an object. Different colors reflect light in different wavelengths, depending on a variety of factors, including the composition of the material reflecting the light.
Petroleum jelly contains phosphors. Phosphors absorb radiation from light and emit it as light we can see. When the petroleum jelly glows, the phosphors are in the process of absorbing the ultraviolet radiation from the black light.
What else seems to glow under a black light? How about a white T-shirt? $20 bill? Experiment with different household objects and record your observations!
