on Thursday, 19 September 2013
When i was in school, i use to think the same question again and again that 'how does data travel though wires',  i was soo crazy to know how copper wires read our data and send to the other end. I know only one thing at that time is  that  electrons  will flow in wires, then how come they carry our 'so called' data particles, do they have brain? do they even remember what we sent and forward to next end, these were my crazy questions.I googled the same question many times but dint get the correct answer at that time,not even now...
It seems very funny, but they were very serious doubts not only me but also within the many  brains, who are not much aware with electronics. So, i'm dedicating this post for those people who are like me.Lets have a look how it happen...
How data transfer through wires:
First thing we need to know that wires or cables dont have brains(smile) yes its true , they dont, you even agree with me after reading this whole post...
Second thing is wires dont know what we are doing,just they are material made of copper(in general).
Before knowing how data transfer occur , we need to know few basic concepts like 'current' and  'voltage'

we know that wire or cable made of copper or any material suitable, they have lot of electrons in it, if electrons flows from one point to other point then it is simply called as Current.
Assume we move from Delhi(place in India) to Mumbai by any vehicle then it is called "Traveling". similarly if electrons move from one point to other it is called Current.
To travel, just by sitting in a bus will not make us to move, but it need to apply some force to move. similarly to move electrons they dont just move ,we need to apply certain force to move them. This force we simply call as Voltage. Voltage is the potential difference or just a force to drive the electrons. How much force we apply that much current(flow of electrons) occur.
There is something called AC and DC i.e Alternating Current and Direct current. I dont make you bore by explaining all these concepts.
Now let us see how data flow occur,
In general we can transmit data by analog form or digital form(dont worry if you dont understand these words). I'll explain in digital form.

Lets take an example of pc keyboard which sends data to its cpu.
Assume we need to send keyboard data  to the cpu and finally on to the monitor screen.It happen by digital form.
Our wire or cable dont know whats this alphabet 'A' or 'B' or 'C'  is, or which key we have pressed on the keyboard, its just transfer the voltage which we applied to that wire.
Digital form is nothing but sending data by 1's and 0's through cable. I know your mind is stuck with a query, what are these ones and zeros. I have explained you before voltage right,now if we apply in between 3v to 5v then it is called '1'  and if we apply 0 to 2v around it is called '0' .
For example we need to send '1' i.e 5v on to the wire, observe below fig.
we just  ON  the 5v supply Switch > electrons will flow > we say that '1' on the wire now,
then if we make switch  OFF  i.e electrons wont flow,i.e we say transmitting '0'
how data travel through wires or cables

we understood how bit  1 and 0 is said to be transmitted then how alphabet A, B, C so on transmitted then how 1,2,3's are transmitted.
Every alphabet have a unique series of ones and zeros, when we press any key on keyboard,a circuitry in the keyboard will release corresponding code(i.e stream of bits),  then series of bits will flow though the wire, and at the receiving end those bits of 1's and 0's are saved. Depending upon which series of zeros and ones are received the corresponding digit or alphabet  shown on screen.
If  we press alphabet 'A' then "11100" will flow, at receiving side there will be a circuitry which checks received is 11100 then it shows as A on to the screen.
Now we know "11100" means " ON, ON, ON, OFF, OFF"
similarly all digits, alphabets and special characters or symbols have different codes few of them are
B=110010, C=100001 , so on.. for each pressed key these will flow ...
Then how it will be known, whether it is capital letter 'A' or small letter 'a' , its simple both of them have different codes..
(Note: The above code for A, B, C  are related to ps2 keyboard not ASCII value)
Now we got clear picture that we are not sending any data, just sending our desired letter one by one in the form of high voltage and low voltage i.e we are calling as 1's ad 0's..
Consider land line phones, in which data will be transmitted some what similar way, at the sending audio will be converted into bits i.e 0 and 1's(electrical form) and at the receiving end they are again converted..   Device which converts to electrical signal is called "transducers"
(Note: There are other techniques to transfer data, just to give a bright picture i have given above examples)
Now you might be understood that wires dont have brains(smile)..