How do electromagnetic waves carry information?

Answer 1

The thing about electromagnetic waves that makes them useful for communication

is that we know how to generate them and how to detect them. As soon as you

have that ability, you're ready to move information from one place to another.

After that, the only question is: How do you put the information onto the waves ?

The answer is: Change something on the waves, according to a pattern that the

sender and the receiver agree on.

What is there about a wave that you can change ? Not much ... only the wave's

amplitude and its frequency (wavelength), and that's it! Can you do anything with

those ?

Example: The easiest way to change the amplitude of the wave is to turn it on and off.

You can use a flashlight or a radio transmitter, turn it on and off in some pattern that

you've worked out. If you use both long and short flashes, you can call it "Morse Code".

If all the flashes are the same length but they come at different times, you can call it

"digital communication". As long as somebody else can see your flashlight or receive

your radio signal, you can send them messages if they understand your patterns.

After that, the sky is the limit. You can get fancy, change the amplitude by small amounts,

change the frequency by large or small amounts, change them fast or slow, change them

both at the same time, and work out ways to load tremendous amounts of information

onto an electromagnetic wave. Once you accomplish that, you earn the right to use

big fancy names for your methods, like 'Amplitude Modulation', 'Frequency Modulation',

'Phase Modulation', and a few of my favorites: 'Seven-level Partial Response Modulation',

'Quadrature Phase Shift Keying', and '256-state Quadrature Amplitude Modulation'.

But all of them are just different systems for changing the amplitude and frequency

of a wave in definite patterns, and it's the patterns that carry the information.

Answer 2

For example, radio waves are used to transmit signals, in radio and television. You can also use light signals; light is a type of electromagnetic wave. For example, when you smile at someone, your smile is communicated to him by means of electromagnetic light waves which are incident on your face, reflected from it, and enter his eyes.

Answer 3

it don't sorry .

Answer 4

Radio waves pass easily through air