Electromagnetic Spectrum for the Middle School Student
Waves are all around us and come in various forms. Sound waves can travel through air because air is made of molecules, which carry the sound. Another type of wave is electromagnetic waves, which are different than 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 empty space (Groleau 2011). The electromagnetic spectrum consists of all waves of energy found in our universe. Radio waves, microwaves, infrared light, visible light, UV light, X-rays, and gamma rays, are the are the most common wavelengths on the spectrum. Wavelength is the distance between one wave crest (peak) to the next. Waves in the electromagnetic spectrum vary in size-- from very long radio waves the size of buildings, to very short gamma rays smaller than the size of the nucleus of an atom. But you may ask, are all of these waves that different from one another? The answer in fact, is no! What differentiates these types of waves is the amount of energy they carry. Photons, the smallest massless unit of energy, bundle up and travel in waves. The amount of photons that travel are measured and classified by the energy they posses. As the wavelength of the waves decrease, the amount of energy of the photons increases (Bitesize 2011).
The visible eye can detect waves lengths between .4 millimeters and .7 millimeters long (Groleau 2011). We call this visible light. Look around you-- everything you see has waves of light bouncing off of it that your eyes detect and turn to images in your brain. Waves measuring less than .4 millimeters long are considered ultraviolet (UV) waves (Bitesize 2011). These short waves are unsafe to living organisms. Most life forms that are exposed to UV light can be hurt and even killed. The sun is a great source of ultraviolet radiation. In fact, UV rays cause our skin to burn if we do not use proper protection! Another type of wave are infrared waves, commonly referred to as heat rays. The heat we feel when we’re near a fire is an example of infrared. If we could see infrared, we would be able to see heat coming off of things around us. Our skin emits heat in the form of infrared light. This is how people using night vision goggles are able to see us in the dark. The hotter the object, the more energy it has. Only extremely hot objects or particles moving at very high speeds can create high-energy radiation like X-rays and gamma rays (Seely 1979). Doctors use X-rays to look at your bones and dentist use them to look at your teeth. Gamma rays are the most energetic waves in the electromagnetic spectrum. They are created mostly by radioactive materials but also by our universe ("Electromagnetic Spectrum - Introduction." 2011)!
"BBC - GCSE Bitesize: What is a spectrum?." BBC - Homepage. N.p., n.d. Web. 26 Oct. 2011....