how do bits work

[Lao Tzu]

i have a data transfer question.

how exactly are bits read by the recieving computer?

a 56k modem can, i guess, read up to 56,000 bits a second. but how. does the electrical wire send 56000 on/off signals per second?

do fiber optic cables work by sending up to 10 billion (OC192) on/off lights per second?

 

[Punschkrapfen]

it can only do ~2400 bits per second = on/off signals per second = amplitude modulation. Higher speeds can only be achieved by combining this with frequency modulation. read
http://www.delmar.edu/Courses/CIS415L/KeyTerm3.htm

and also for example
http://www.tscnet.com/user/k56flex/cmodem.html
http://home.earthlink.net/~mjohnsn/Modems.html
http://www.students.tut.fi/~best/sc/sc95/wernermodem.html

56k only works downstream, when the ISP is fully digital. 33.6k is the limit for analog-to-analog connections over 3khz telephone wire. This cannot be extended due to the limited bandwith of analog telephone channels. Only xDSL opens the bandwith barrier and allows much higher transfer rates.