What is the (approximate) speed of a telephone signal?

Question

I think it is the speed of sound (340 m/s) am i correct?

Answer 1

Many telephone signals nowadays travel by optical fibre, where the speed is the speed of light in the particular kind of glass, i.e. of the order of 2/3 the speed of light in a vacuum.

Where the signal still travels by conventional wires, the formula for the speed is complicated and depends on the insulation and the configuration of the wires - but it's still comparable to the speed of light, not the speed of sound.

Where microwave links are used, the speed is indeed the speed of light in air.

Answer 2

It would be the speed of light in various mediums, like copper, gold and silica &/or plastic.

Answer 3

the external 'signal' or sound which you can hear is audio and travels at the speed of sound ( it is in fact 'sound').

  the internal signal (electrical) travels at the same rate as any electrical pulse and that is very fast but there are some conductors that allow a faster travel but the amount is  an a very small amount of time such as nanoseconds.

  in space ( complete vacuum)  an electrical pulse  travels at sped of light ( 186.000 miles a second) but  in a medium such as copper etc  it loses some speed due to resistance of the medium its travelling through. ( around 0.2%)

  with a super conductor (  copper etc cooled with liquid nitrogen etc) it  acts a sthough there si sno resistance at all and travels again at speed of light.

Answer 4

If your signal is going from cell phone to cell phone its slightly less that the speed of light

Answer 5

No, it's much faster than that. It only travels at the speed of sound between your mouth/ear and the handset (when it IS sound) - after that the sound is converted into an electrical signal. With a wired telephone, the speed of propagation in a copper wire is about two-thirds light speed (approx 4470 million mph), and the same when the signal is converted to light and sent along optical fibre (light moves slower through glass). Any portion of the journey that is wireless (radio/microwaves) would be near 100% light speed (670 million mph). Delays get introduced where the signal passes through switching equipment, and an international phone call that has to go via satellite suffers a significant delay as it has to cross the distance between Earth and the satellite and back.

Your question reminded me of an interesting effect you can get if you listen to a clock chiming live and over the radio simultaneously (like the chiming of Big Ben at New Year) - if the microphone relaying the sound is closer to the bell than you are, the signal will reach the radio before the real sound reaches your ears, even though it has to go via the radio studio and a radio transmitter somewhere!

Answer 6

No, it's sent down a telephone via an electrical current, meaning it travels at near the speed of light.

Answer 7

If that were true, it would take 4 hours for your "hello" to reach LA in CA from NY city.  BIG phone bill.

Since the phone using electrical current, the speed of the EM (electromagnetic) wave is near the speed of light.  It actually takes does not go quite that fast because of signal processing and  resistance.

What is sort of "cool" is that the individual electrons in the wire drift very slowly (a few cm an hour) but their EM wave is near light speed.  Another "oddity" of electro-magnetism.

Answer 8

Light speed, but it gets delayed by switching equipment going through exchanges/satellites etc.

If it was the speed of sound, when you phoned someone in Australia it would take hours for your voice to arrive and for you to get an answer!

Answer 9

No, it is not.

The signal that travels the phone line is digital, i.e. it is the speed of the electrons, and light.

~300,000 km/sec