# What do you understand by electromagnetic waves.Give its properties

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## 1 Answers

Apoorva Arora IIT Roorkee
askIITians Faculty 181 Points
10 years ago
The range of wavelengths for electromagnetic waves--from the very long to the very short--is called the Electromagnetic Spectrum:
RadioandTVwaves are the longest usable waves, having a wavelength of 1 mile (1.5 kilometer) or more.
Microwavesare used in telecommunication as well as for cooking food.
Infraredwaves are barely visible. They are the deep red rays you get from a heat lamp.
Visible lightwaves are the radiation you can see with your eyes. Their wavelengths are in the range of 1/1000 centimeter.
Ultravioletrays are what give you sunburn and are used in "black lights" that make objects glow.
X-raysgo through the body and are used for medical purposes.
Gamma raysare dangerous rays coming from nuclear reactors and atomic bombs. They have the shortest wavelength in the electromagnetic spectrum of about 1/10,000,000 centimeter.
Electromagnetic waves are transverse waves, similar to water waves in the ocean or the waves seen on a guitar string. This is as opposed to the compression waves of sound. As you learned in Wave motion, all waves have amplitude, wavelength, velocity and frequency.
Amplitude
The amplitude of electromagnetic waves relates to its intensity or brightness (as in the case of visible light).
With visible light, the brightness is usually measured in lumens. With other wavelengths the intensity of the radiation, which is power per unit area or watts per square meter is used. The square of the amplitude of a wave is the intensity.
Wavelength
The wavelengths of electromagnetic waves go from extremely long to extremely short and everything in between. The wavelengths determine how matter responds to the electromagnetic wave, and those characteristics determine the name we give that particular group of wavelengths.
Velocity
The velocity of electromagnetic waves in a vacuum is approximately 186,000 miles per second or 300,000 kilometers per second, the same as the speed of light. When these waves pass through matter, they slow down slightly, according to their wavelength.
Frequency
The frequency of any waveform equals the velocity divided by the wavelength. The units of measurement are in cycles per second or Hertz.
Thanks and Regards
Apoorva Arora
IIT Roorkee
askIITians Faculty

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