Electromagnetic spectrum for the middle school student Waves surround us and come in various forms. Sound waves can travel through air because air is made of molecules that carry sound. Another type of wave is electromagnetic waves, which are different from sound waves because they don't need molecules to travel. This means that electromagnetic waves can travel through air and solid materials as well as in empty space (Groleau 2011). The electromagnetic spectrum is made up of all the energy waves present in our universe. Radio waves, microwaves, infrared light, visible light, UV light, X-rays, and gamma rays are the most common wavelengths of the spectrum. Wavelength is the distance between one wave crest (peak) and the next. Waves in the electromagnetic spectrum vary in size: from very long radio waves, the size of a building, to very short gamma rays, smaller than the size of the nucleus of an atom. But you might ask: are all these waves that different from each other? In fact, the answer is no! What differentiates these types of waves is the amount of energy they carry. Photons, the smallest massless unit of energy, clump together and travel in waves. The amount of photons traveling is measured and classified based on the energy it has. As the wavelength of the waves decreases, the amount of energy in the photons increases (Bitesize 2011). The visible eye can detect wavelengths between 0.4 millimeters and 0.7 millimeters in length (Groleau 2011). We call this visible light. Look around you: everything you see has waves of light bouncing off it that your eyes detect and turn into images in your brain. Waves that measure less than 0.4 millimeters in length are considered ultraviolet (UV) waves (Bitesize 2011). These...... half of the paper...... Works Cited"BBC - GCSE Bitesize: What is a spectrum?" BBC - Home page. Np, nd Web. October 26, 2011. "Electromagnetic Spectrum - Introduction." Imagine the Universe! Home page. Np, nd Web. October 26, 2011. .Groleau, Rick. "NOVA | Electromagnetic Spectrum Tour." PBS: Public Broadcasting Service. Np, nd Web. October 26, 2011. Seely, Samuel, and Alexander Poularikas. Electromagnetism: classical and modern theory and applications. New York: M. Dekker, 1979. “Blue Shift” print. Universe Today - Space and astronomy news. Np, nd Web. October 31. 2011. .