# What Do Electromagnetic Waves Consist Of? How Are They Produced? How Are They Transmitted And Received? What Are Their Properties? How Are They Used In Communication? How Does Energy Conversion Happen In Wireless Communication?

UNITS
m = meters  hz = hertz = how many complete cycles a wave completes per second.
Nanometer = 1 billionth of a meter or  1.0x10^-9m

VARIABLES
C = the speed of light approx. 300,000,000 m/s (300,000 km/s) or 186,000 miles/second.  Yeah thats pretty darn fast.
F = frequency  Lower case Lambda = wavelength, the Greek letter that I can't draw or insert in the text box.  Just google image Lambda if you want to see the symbol.

Electromagnetic waves are essentially light waves and vary in length and frequency(energy).  High energy = high frequency, short wavelength   Low energy = low frequency, longer wavelength.  They are produced a multitude of ways for example an incandescent light bulb    ( the everyday light bulb) uses electricity, which are also considered a form of electromagnetic waves (electromagnetic radiation) to heat, or excite, a special filament (usually tungsten coated) inside the bulb which releases a visible light which is in the range of 400-800 nanometers or 4x10^-6 m to 8x10^-6 m in length and approx. 3x10^14 hz or 300,000,000,000,000 hertz or 300 trillion hertz.
The sun is a major contributor to electromagnetic radiation on earth; more specifically in descending order from higher to lower energy: Cosmic, gamma, x-ray, UV (ultra violet), visible light, infrared, and microwaves.  Heat sources while capable of emitting visible light, also creates what is called infrared radiation, which is almost entirely invisible to the naked eye.  Have you ever seen the squiggly lines what most people refer to as heat waves coming out of the hood of your car in the summer.  That is infrared radiation which can damage your eyes if the concentration is high enough (if the source is hot enough).  This can be dangerous because as I said they are largely undetectable by the naked eye.
The higher the frequency the more energy and shorter wavelength light will have.  In cases of extremely high frequencies for example UV (ultra violet), x-rays, gamma rays, and cosmic rays all have a frequency of greater than 3x10^14 m.  Because of these high frequencies the light waves can penetrate though cells and cause damage.  For example, ever wonder why you get sunburn.  UV radiation emitted from the sun is not fully stopped by our atmosphere which causes it to hit your skin and if exposed long enough gives us sunburn.  This would be the light destroying skin cells.  When you get into even higher frequencies 3x10^15 hz + like x-rays, gamma rays, and cosmic rays these forms of light are powerful enough to penetrate right through your entire body destroying or mutating cells if exposed long enough.  Luckily for us the atmosphere stops these extremely dangerous light rays from contacting us down here on the surface.  On the flip side of high power short length electromagnetic waves there is light with longer wavelengths and lower frequencies than visible light.  In descending order of frequency infrared, microwave, TV and radio, and electricity.  Theres a few more very specific types in there, but you get the gist.