At-Home STEM Activities: DIY Spectroscope
Split sunlight into all the beautiful colors of the spectrum, with a homemade spectroscope! This activity takes just a few minutes, and utilizes common household items. Adult supervision is required—we’ll be cutting cardboard with a craft knife.
Introduction
When the sunlight shines on us, it sends every color together in what is known as white light. White light is made up of many colors with different wavelengths and frequencies, but unless they are separated, we can’t see them all.
A spectroscope, or spectrometer, splits light into the wavelengths that make it up. Early spectroscopes used prisms that split the light by refraction—bending the light waves as they passed through glass. A good example of refraction in nature is a rainbow: sunlight passes through raindrops and is split into its different colors.
A prism splits white light into the different colors & wavelengths that make it up (image credit: nasa)
Materials:
Empty paper towel roll or cylindrical potato chip can—see Notes below
Craft (X-Acto) knife or sharp scissors (for adult use only)
Pencil/writing implement
Compact disc
Tape
Small piece of cardboard or cardstock
Paint/decorative materials (optional)
Note: We tried 2 versions of this activity, one with a paper towel roll and one with an empty Pringles potato chip can. Both versions worked equally well—so it’s all a matter of what materials you have on hand to work with! If you want to decorate your spectroscope, apply paint and other decorations before starting construction.
Procedure
Have an adult cut an arch-shaped slit in one end of the paper towel roll/Pringles can. The two ends of the “U” should be pointing downward toward the end of the tube, and at a 45-degree angle to the length of the tube—as pictured. This is your CD holding slot.
Then cut a small rectangle out of the end of the tube, opposite the slit that you cut in Step 1. This is your viewing window.
For paper towel roll version: use a writing implement to trace the circumference of the tube onto a small piece of cardboard. Cut out the circle, and then cut a small rectangular slot in the center of the circle.
For Pringles can version: keep the plastic lid on the can, and cut rectangular slot into this.
For paper towel roll version: use tape to secure the cardboard circle to the top of the paper towel roll (the end OPPOSITE the viewing window and CD slot), without covering up the slit that you cut in the last step.
For Pringles can version: use tape (blue painter’s tape is a great option) to cover the lid all around the slot, to make sure that sunlight only enters your scope through the slit in the lid and not through the material of the lid itself
Insert the CD into the holder slot, with the reflective side facing up
Take your spectroscope outside, and hold upright, so that sunlight enters through the slit in the top, reflects off of the CD, and is visible in the viewing window. Never look directly at the sun!
You should see a rainbow, as the sunlight is broken into all its different wavelengths!
How Does It Work?
A CD may look and feel smooth, but it actually has tiny ridges that diffract (spread and separate) sunlight. Because all the colors that make up sunlight have different frequencies, they will diffract at different angles, and appear as a rainbow.
