Electromagnetic Spectrum
Electromagnetic Spectrum is the full range of light and energy, from radio waves to gamma rays, mostly invisible to our eyes.
A kitchen drawer holds many utensils, each a different size. Radio waves are like the long wooden spoons at the back — big and slow. Visible light is like the forks and knives in the middle. Gamma rays are like tiny toothpicks up front — small but packed with energy.
Explaining electromagnetic spectrum by grade level
Light comes in many forms, but your eyes only see a small part. A star's color tells you how hot it is. Blue stars burn hotter than red ones. Other kinds of light, like radio waves, are all around you but stay hidden from sight.
Projects that explore electromagnetic spectrum
The full range of light and energy stretches beyond what our eyes can see. Splitting sunlight with a prism and placing thermometers in each color band shows that temperature rises from blue to red. The thermometer set just past the red, where no color is visible, reads even higher. This proves that invisible infrared radiation carries more heat than visible light.
The full range of energy includes ultraviolet and infrared light, which sit at different positions in the spectrum. You charge identical glow-in-the-dark stickers with four different lamps and time how long each glow lasts. The stickers charged by ultraviolet light keep glowing far longer than the rest, while infrared-charged stickers fade the fastest.
The full range of energy includes visible light, and water treats each part of that range differently. A scuba diver photographs red, yellow, green, and blue metal balls at four depths from 5 to 20 meters, revealing that water removes colors unevenly. The photos show that red and yellow balls lose their visible color by 15 to 20 meters, while green and blue remain visible at all tested depths.
The full range of energy includes UV rays that can cause skin damage. Different types of glass filter out different amounts of UV. You place a UV meter inside a wooden box in direct sunlight. Then you cover it with one glass type at a time to measure how much UV passes through.
A star's color tells you how hot it is. Blue stars burn far hotter than red ones, because color corresponds to the wavelength of light a star emits. Within the full range of energy from radio waves to gamma rays, only a small portion produces the visible color you see in telescope images. When you analyze stars, nebulae, and galaxies, differences in color directly reflect differences in temperature and composition.