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21 Nov 2012

Electromagnetic radiation (EMR) is one of those phrases that just sounds threatening. However, without it, the world around us would not even exist. EMR is actually a spectrum that encompasses all forms of energy. Light itself is part of the Electromagnetic Spectrum (EMS). The reason we see colors is that everything around us emits, reflects, and absorbs EMR, depending on its composition. The reason we see a leaf as green is that the chlorophyll is absorbing all other colors on the light spectrum except the color green, which it then reflects. The simplest way to understand EMR is to break it down into the components of its spectrum.

All energy consists of waves that have dips and crests exactly like the waves of the ocean. Waves are measured by the number of crests that pass by in a single second, known as hertz. The longer the wave is the lower its frequency and the less energy that it carries. The longest wave on the Electromagnetic Spectrum is radio waves. Radio waves are a form of energy that can range in length from the length of a water bottle to being longer than the Earth itself. Radio waves were first discovered in 1888, and by the 1920s, the first public radio station was broadcasting music over the air. Radio waves are silent; you aren’t actually hearing radio waves on a radio. The radio is receiving electromagnetic radiation (or waves) and then it vibrates the speaker to “translate” the wave into sound. Radio waves aren’t just limited to the latest hit music station. Stars also generate radio waves; giant dishes the length of 3 football fields detect such giant waves. 

Microwaves are another form of electromagnetic radiation, ones that many people are familiar with in their day-to-day lives. However, microwaves aren’t just limited to heating up last night’s leftovers. Speed radar, phones, WiFi and Doppler radar used in weather forecasting also use microwaves. Microwaves vary in length from a millimeter to the size of a ruler. They are banded into different “families.” For example, C-band microwaves can penetrate through clouds and land to give us a view of changes in the ocean. L-band microwaves are used by GPS to detect topography.

Infrared is close to our visible spectrum and lies just outside of what we can see, similar to ultraviolet light. There are two types of infrared: far and short. This relates to their wavelengths. Far infrared is also known as thermal radiation and is generated by heat. If you look at an infrared detector, warmer areas light up bright orange, while cooler areas remain blue; this literally means that the warmer areas are generating more electromagnetic radiation. Short infrared is the same kind we use in our television remotes.

Finally, gamma rays are the most intense form of electromagnetic radiationand are the most dangerous. Gamma rays have the shortest wave and are so small that they actually pass through atoms. This makes them incredibly difficult to detect. They are created by nuclear explosions, radioactive decay, and even thunderstorms. Gamma ray bursts, caused by stars and supernovas, can release more energy in 10 seconds than our sun will emit in its life cycle. While they may not turn you into The Hulk, gamma rays can be beneficial since they are harnessed and “shot” into cancer patients to kill cancer cells.

It’s because of electromagnetic radiation that we can see and communicate. These days we are awash in radiation generated from our laptops, tablets and cell phones. Sure, these things would not be able to function without electromagnetic radiation, but it is still safe to limit our exposure to them as much as possible.