How Fast is elcectricity

[nexium]

As I recal from my transmission lines course in college in 1956, most metalic circuits transfered data slower than 0.95 c. It is hazy, but I recall about 0.5 c being typical. with components of most kinds causing additional delay. The inductance is one of the causes of delay. Frequencies as low as a trillionth of a hertz have been theororized, and may actually propagate thoughout the galaxy. It is thought that they behave much like higher frequencies except for the extremely long wave length, so I would say the theshold is at f = zero. Typically a pulse burst travels on a dc line when ever the current is switched on or switched off. Neil

 

[seppstefano]

Hi Neil,<br />many thanks. So, in case of audio range frequencies (from around 20Hz, up) , I understand it would be reasonable to assume the validity of second formula, wouldn't it?<br /><br />Stefano

 

[nexium]

Hi seppstefano: I think the only transition near 20Hz is human hearing. I'll guess 0.1% skin effect at 3,000,000Hz = 3 megahetz. Up to 30 megahertz is called high frequency by the FCC = Federal Communications Commission. Skin effect may not reach 10% until 3000 megahertz which is the top of the UHF = ultra high frequency band. The transition is quite gradual. Wave guides are sometimes used above this frequency, but computers now operate up to 30,000 (?) megahertz = 30 gigahertz without wave guides, but distance is typically in nanometers to reduce delay and attenuation. Neil

 

[seppstefano]

Thank you Neil,<br /><br />Stefano

 

[pyoko]

Way back in high school, they told me it was instantaneous, because current is like "water pressure in a garden hose" Also, this screen/ graphics card is so stuffed, I cant even see what I'm typing (caffe). <div class="Discussion_UserSignature"> <p> </p><p> </p><p><span style="color:#ff9900" class="Apple-style-span">-pyoko</span> <span style="color:#333333" class="Apple-style-span">the</span> <span style="color:#339966" class="Apple-style-span">duck </span></p><p><span style="color:#339966" class="Apple-style-span"><span style="color:#808080;font-style:italic" class="Apple-style-span">It is by will alone I set my mind in motion.</span></span></p> </div>

 

[dragon04]

<font color="yellow">Way back in high school, they told me it was instantaneous, because current is like "water pressure in a garden hose"</font><br /><br />In the case of electrical conductors, that's at least partially true due to the stored charge (capacitance) in a conductor. However, the current would be low compared to the load that the device requires on the end.<br /><br />But that doesn't explain the "speed" of electricity even in a conductor. Yes, the conductor has an "idle" charge, but that doesn't quantify the flow rate once the circuit is in operation.<br /><br />In other words, yes. The "full hose" supplies "immediate" water, but the flow rate of that water after pressure is applied is not determined. The actual flow rate is determined by the pressure applied, and the friction loss involved.<br /><br />Electrical, hydraulic and pneumatic circuits all obey the same set of rules, and the formulae are identical although expressed in different terms.<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[nexium]

Actually the full hose hose does not supply water instantly. The pressure increase travels down the hose at several thousand miles per hour (slower if there are air bubbles) So the water starts flowing from the far end after a milisecond delay. Delay depends mostly on the length of the hose. Electricity is faster, taking about one microsecond to reach the end of a 1/10 mile extention cord = one second for a 100,000 mile extention cord. The electrons bump each other along the wire, so the average progress of the electrons inside the wire is only a few thousand miles per hour. Neil