Light is a kind of energy called electromagnetic radiation. There are many different forms of electromagnetic radiation, such as radio waves, microwaves, ultraviolet rays, and X-rays. Each form is characterized by a different wavelength. For example, radio waves can be several miles long, while gamma rays are smaller than atoms. The light that we see — visible light — falls somewhere in the middle of this "electromagnetic spectrum."
Visible light may be a tiny part of the electromagnetic spectrum, but there are still many variations of wavelengths. We see these variations as colors. On one end of the spectrum is red light, with the longest wavelength. Blue or violet light has the shortest wavelength. White light is a combination of all colors in the color spectrum. It has all the colors of the rainbow. Combining primary colors of light like red, blue, and green creates secondary colors: yellow, cyan, and magenta. All other colors can be broken down into different combinations of the three primary colors.
Objects appear one color or another because of how they reflect and absorb certain colors of light. For example, a red wagon looks red because it reflects red light and absorbs blue and green light. A yellow banana reflects red and green light, and absorbs the rest.
** What You'll Need ?
>> 1 white paper cup
>> Red, green, and blue markers
>> Strand of brightly colored holiday tree lights
>> 1 pencil or pen
** What to do?
Color the inside of a white paper cup with the three primary colors of light: red, blue, and green. Leave one of the stripes white (There should be four equal stripes in red, blue, green, and white.)
Use a pencil to punch a hole in the bottom of the cup.
Plug in the strand of holiday lights. Take a red light from the strand and stick it through the hole in the bottom of the cup.
Look at the red, blue, and green sections in the cup. (NOTE: For better results, turn off the room light.)
What happens to the colors inside the cup? Do they still look the same, or do the colors in the cup change?
Try the experiment using the blue and green lights. What happens to the colors inside the cup? Use what you learned about the colors of light to explain why the colors change.
A Sight to Behold
Human eyes can detect only certain wavelengths, so visible light is the only kind of electromagnetic radiation we can see. Some animals can see other forms of light. Bees and butterflies can see ultraviolet light, which means that they see different colors than we. This helps them find flowers to pollinate. The world must look pretty different from a bumblebee's perspective!