Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I've been a programmer for a while, and I've done a little bit of network programming, but I'm wondering, how do bits get transferred over a copper wire?

What counts for a 1 & what counts for a 0?

I don't know a lot of physics so explain to me as if I were a 8 year old please :)

share|cite|improve this question
up vote 1 down vote accepted

You won't be surprised to learn it's just varying voltage levels in a circuit formed by the network cables. You also probably won't be surprised to find that the details are fiendishly complicated and far too involved to reproduce here. Even the voltage levels used depend on whether it's 10MHz, 100MHz or GHz cabling. GHz uses five voltage levels and pulse amplitude modulation.

The simplest starting point is probably the Wikipedia article on Ethernet over twisted pair. If you want to know more about how the information is encoded look at the Cisco article on Ethernet.

You might also want to ask on a different SE site e.g. Electrical Engineering or Server Fault.

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.