What is Electromagnetic Waves?
An electromagnetic wave is an energy waveform that has both an electric and a magnetic field. Electromagnetic waves differ from mechanical waves in that they can transmit energy and travel in a vacuum.
Types of Electromagnetic Waves
Electromagnetic waves are classified according to their frequency. Different types of waves have different uses and functions in our daily lives. The most important of these is visible light, which allows us to see.
Radio Waves
Radio waves have the longest wavelength of all types of electromagnetic waves. They range from about a foot long to several miles. Radio waves are commonly used to transmit data and have been used for all kinds of applications including radio, satellite, radar and computer networks.
Microwaves
Microwaves are shorter than radio waves with wavelengths measured in centimeters. We use microwaves to cook food, transmit information and radar to help predict the weather. Microwaves are very useful in communication because they can penetrate clouds, smoke and light rain. The universe is filled with cosmic microwave background radiation that scientists believe is a clue to the origin of the universe, which they call the Big Bang.
Infrared
Between microwaves and visible light are infrared waves. Infrared waves are sometimes classified as “near” and “far” infrared. Near-infrared waves are the closest waves to visible light in wavelength. Infrared waves are used in the TV remote control to change the channel. Infrared waves are far from visible light in terms of wavelength. Far infrared waves are thermal and exothermic. Anything that gives off heat emits infrared waves. This includes the human body!
Visible light
The visible light spectrum includes wavelengths that can be seen by the human eye. That is the wavelength range from 390 to 700 nm corresponding to the frequency 430-790 THz. You can go here to learn more about the visible spectrum.
Ultraviolet
Ultraviolet waves have the next shortest wavelength after visible light. It is the sun’s ultraviolet rays that cause sunburn. We are protected from the sun’s ultraviolet rays by the ozone layer. Some insects, such as wasps, can see ultraviolet light. Ultraviolet light is used by powerful telescopes such as the Hubble Space Telescope to observe distant stars.
X-rays
X-rays have even shorter wavelengths than ultraviolet rays. At this point in the electromagnetic spectrum, scientists began to treat these rays more like particles than waves. X-rays were discovered by German scientist Wilhelm Roentgen. They can penetrate soft tissues such as skin and muscle and are used to take x-ray images of bones in medicine.
Gamma rays
As the wavelengths of electromagnetic waves shorten, their energy increases. Gamma rays are the shortest waves in the spectrum and therefore have the most energy. Gamma rays are sometimes used in cancer treatment and detailed imaging for diagnostic medicine. Gamma rays are produced in high-energy nuclear explosions and supernovas.