What is electromagnetic radiation?
Electromagnetic radiation consists of a wave motion in both electric and magnetic fields. These fields oscillate at a common frequency at right angle to each other, and at right angle to the direction of motion. The higher the frequency, the higher the energy. Some examples of electromagnetic radiations are radio waves, microwaves (“T.V.waves”), infra- red rays, visible light, ultra-violet rays, X-rays and gamma rays.
Across all of the spectrum, the electromagnetic spectrum, we’ll grab a band of frequencies and generate the waves to use them for different things. You already know the benefits of radio waves and microwaves. And you’ve used the optical spectrum all your life. X-rays are something you know of as well. And the gamma rays, which are generated by changes in atomic nuclei, pass through you all the time because of natural radiation. There is more to learn, and links are provided below to get you further down the road.
A lot of people seem to associate radiation with nuclear waste and things that cause cancer. However, in science, it has a much more general definition. Radiation is a way to transfer energy and have it propagate, or spread out, as it travels. Now that you know light is a form a radiation, you can see evidence of this every time you use a flash light. Notice how the beam’s diameter increases the farther it is away from the source? This is a property of a wave (which will be discussed in more detail in section 1.1.1 – What is a wave?). As for the “electromagnetic” part, that refers to the fluctuating electric and magnetic fields that make up the waves. The Speed Limit of the Universe Aside from the fact that all EM (electromagnetic) radiation are composed of varying electric and magnetic fields that spread out as they travel, there is one other very important similarity between all of them; they all travel at the speed of light. The fact that there is a speed of light means that light d
