What are the frequencies of current in computers' external peripheral cables and internal buses?

Question

From Wikipedia, three different cases of current frequency are discussed along with the types of cables that are suitable for them:

An Extra Ordinary electrical cables suffice to carry low frequency AC, such as mains power, which reverses direction 100 to 120 times per second (cycling 50 to 60 times per second).

However, they cannot be used to carry currents in the radio frequency range or higher, which reverse direction millions to billions of times per second, because the energy tends to radiate off the cable as radio waves, causing power losses. Radio frequency currents also tend to reflect from discontinuities in the cable such as connectors, and travel back down the cable toward the source. These reflections act as bottlenecks, preventing the power from reaching the destination. Transmission lines use specialized construction such as precise conductor dimensions and spacing, and impedance matching, to carry electromagnetic signals with minimal reflections and power losses. Types of transmission line include ladder line, coaxial cable, dielectric slabs, stripline, optical fiber, and waveguides. The higher the frequency, the shorter are the waves in a transmission medium. Transmission lines must be used when the frequency is high enough that the wavelength of the waves begins to approach the length of the cable used.

To conduct energy at frequencies above the radio range, such as millimeter waves, infrared, and light, the waves become much smaller than the dimensions of the structures used to guide them, so transmission line techniques become inadequate and the methods of optics are used.

I wonder what the frequencies are for the currents in computers' external peripheral cables, such as Ethernet cable, USB cable, and in computers' internal buses? Are the cables also made specially for the frequencies?

Thanks!

Answer 1

I wonder what the frequencies are for the currents in computers' external peripheral cables, such as Ethernet cable, USB cable, and in computers' internal buses?

This information should be available in either the appropriate Wikipedia articles or in the relevant technical standards (which are probably referred to in those articles)

In general the signalling rate or frequency is not the same as the data rate (due to encoding, the use of multiple transmission channels (e.g. pairs) and other factors) but dividing by ten will give you a (very) rough idea.

For example, 1000Base-T Ethernet has a data rate of 10^9 bits/second, so you could assume a signalling frequency that is 100 MHz.

For the actual rate, use Google (which would lead you to relevant articles)

Are the cables also made specially for the frequencies?

Yes.

Sometimes the data transmission standards are made to match an existing cable specification. For example, I believe the original 10Base-T spec was designed so people could use existing premises wiring standards that had been designed for voice telephony not for Ethernet. This reduced the cost of deploying 10Base-T and may (in a small way) have helped sales of Ethernet products.

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Update:

If you want a rigorous answer, be careful about using vague terms like electricity.

Note that (so far as I know) most electrical signalling systems used with computer peripherals nowadays look at voltage changes at specific frequencies, they don't look at current (c.f. current-loop interface). So it isn't useful to think of "current frequency".

Note: I am not an electronic engineer.