Radar: Electromagnetic Waves

    Radar: Electromagnetic Waves

      Electricity powers everything from the blender in your kitchen to the phone in your pocket to the website you visit to find out if your cell phone would blend. Electricity's great as long as you don't mix it up with magnets. Put those two together, and you could get some serious interference between them.

      But…the forces behind electricity and magnets can make some pretty powerful waves in the electronics industry. Literally.

      Electromagnetism happens when electric and magnetic fields interact, creating alternating currents. When they make electromagnetic waves, they're actually two perpendicular waves tied together. That's just the definition of an electromagnetic wave.

      We are literally immersed in a soup of both natural and man-made electromagnetic waves. Yeah, they're that common. When we talk about these waves, we'll use the fact that the speed of light (c) is constant, but the wave's frequency (using Hertz as the measurement) and wavelength (using meters as the measurement) are the parts changing. The longer the wavelength, the longer it takes the wave to cycle through that wavelength. On the opposite end, the shorter the wavelength, the higher the frequency. We can generalize the relationship with this equation:

      c = λf

      where λ is the wavelength and f is…the frequency. The two multiply together to always give you the same speed. Light speed.

      For these waves to be created, you need a whole lot of energy and heat. For example, a very strong gamma ray (the highest frequency wave) could theoretically break apart your DNA, but creating it means having heat that measures in mega-Kelvins—which is millions of degrees (for perspective, the sun's less than 6,000° Kelvin). Your DNA's safe, Shmooper.

      For now.

      If a wave's really long (in terms of wavelength), it can pass through materials like clouds or walls. The smaller it gets, the more it can pass through, like clothes and skin.

      When you create an electromagnetic wave, it actually radiates out from the source in a sphere (kind-of like expanding balls). That's why we usually call it electromagnetic radiation: it radiates…radially.

      We've been pounding down that electromagnetic waves travel at the speed of light, but that's only in a vacuum, as in the absence of matter. They slow down when they actually have to pass through matter like water, a wall, or bubble gum. That wave's also going to bend as it moves around the particles in the object. Depending on the frequency of the wave, and sometimes the temperature, a material can slow down the wave enough to stop it completely.

      It all depends on the wave.