Energy as Waves
We use energy every day to run our appliances, fuel our cars, and cook our food. However, only one form of energy can travel through the vacuum of space: Electromagnetic Radiation. There are many different forms of Electromagnetic Radiation (EMR) but the only form visible to human eyes is light. Visible light can come from many sources and can be different colors but it is only a tiny sliver of the total amount of EMR that constantly surrounds us. The Electromagnetic Spectrum displays the entire range of EMR that exists. From radio waves to gamma rays, most of the EMR in the universe is invisible to us but we use it every day! |
Types of Electromagnetic Radiation
Radio Waves: Your favorite radio stations use radio waves to send tunes through the atmosphere and to your radio! As shown in the image to the right, AM radio stations use "amplitude modulation" while FM radio stations use "frequency modulation" to send audio information in each wave. AM stations broadcast at a lower frequency (535 - 1700 kilohertz) and signals can travel long distances from the station because the waves get reflected back to Earth by ions in the atmosphere. FM stations broadcast at a higher frequency (88 - 108 megahertz) and signals are lost when traveling more than 40 miles from the station.
Microwaves: Your microwave oven creates microwaves to heat food by energizing water molecules within the food. Microwaves are also used by the weather radar because they can travel through clouds and light rain. Background Microwave Radiation exists in all parts of our Universe and is evidence of the initial energy of the Big Bang and the expansion of the Universe.
Infrared Radiation: Night vision goggles can see the heat emitted by skin because any object that gives off heat also gives off infrared waves. A television remote control uses specific wavelengths of infrared energy to communicate with a receiver.
Visible Light: Our eyes are able to detect visible light as emitted by stars, light bulbs, and even fireflies.
Ultraviolet Light: Sunburns are caused by the damaging UV rays from the sun but luckily our Ozone layer protects us from the majority of UV rays. Some insects can see in the UV spectrum and this causes them to be drawn to specific flowers.
X-Rays: Doctors use x-rays to see through soft tissue to find broken bones while airport security uses x-rays to look for weapons and other items made of metal.
Gamma Rays: Doctors can also use gamma rays to see inside the human body using a positron emission tomography (PET) scan to look for cancer. Gammas are also produced by high energy nuclear explosions and supernovae.
Radio Waves: Your favorite radio stations use radio waves to send tunes through the atmosphere and to your radio! As shown in the image to the right, AM radio stations use "amplitude modulation" while FM radio stations use "frequency modulation" to send audio information in each wave. AM stations broadcast at a lower frequency (535 - 1700 kilohertz) and signals can travel long distances from the station because the waves get reflected back to Earth by ions in the atmosphere. FM stations broadcast at a higher frequency (88 - 108 megahertz) and signals are lost when traveling more than 40 miles from the station.
Microwaves: Your microwave oven creates microwaves to heat food by energizing water molecules within the food. Microwaves are also used by the weather radar because they can travel through clouds and light rain. Background Microwave Radiation exists in all parts of our Universe and is evidence of the initial energy of the Big Bang and the expansion of the Universe.
Infrared Radiation: Night vision goggles can see the heat emitted by skin because any object that gives off heat also gives off infrared waves. A television remote control uses specific wavelengths of infrared energy to communicate with a receiver.
Visible Light: Our eyes are able to detect visible light as emitted by stars, light bulbs, and even fireflies.
Ultraviolet Light: Sunburns are caused by the damaging UV rays from the sun but luckily our Ozone layer protects us from the majority of UV rays. Some insects can see in the UV spectrum and this causes them to be drawn to specific flowers.
X-Rays: Doctors use x-rays to see through soft tissue to find broken bones while airport security uses x-rays to look for weapons and other items made of metal.
Gamma Rays: Doctors can also use gamma rays to see inside the human body using a positron emission tomography (PET) scan to look for cancer. Gammas are also produced by high energy nuclear explosions and supernovae.
WATCH: Electromagnetic Spectrum Videos
ONLINE PRACTICE:
Try these online practice quizzes to gauge your understanding: Spectrum Quiz
Try these online practice quizzes to gauge your understanding: Spectrum Quiz
Discussion Questions:
- On faucets, blue means Cold while red means Hot (high energy). Explain why this is backwards in terms of light energy.
- What weather condition has the greatest impact on cellular service? Why? (do some research!)
- Do some research and list the types of EM Radiation produced/used in the following situations: