How fast data travel wirelessly than in metal? does both travel in the speed of light?

3 Answers 3


Electrical signals basically move at the speed of light in that particular medium. In (copper) wires that is usually around 70% - 90% of the speed of ligth (in a vacuum) or around 200,000km/s - 250,000km/s as opposed to the around 300,000km/s which light travels in vacuum. [Velocity Factor]

Even the speed of light is not constant as is often referenced. The speed of light in a vacuum is constant and it is the maximum speed to transfer usefull information. Still even light can be slowed down (a recent experiment even stopped it for some very short time article youtube ) and it can even go faster than the vacuum speed (see Faster than light speed).

Relevant to your question is, that information information travels in the speed of it's medium. Light in glass travels slower than in vacuum. Electricity in copper wires travels slower than c meaning it is slower than "light speed". But it may travel slower or faster in water, iron, etc. It depends on the medium it is traveling through.

According to How fast does light travel through a fibre optics cable due to reflections and bending of the fibre optics, such signals also travel about 30% slower than the speed of light in vacuum. That means both signals are about as fast as each other.

Remember that light is also an electro-magnetic wave. Thus is travels at light-speed in vacuum, but in a fibre-optic cable you basically send it through air, while in a copper wire, you send it through copper. As for data transmission, that depends on the transmission frequency, dampening and bandwidth of the signal and medium.


Radio waves travel at the speed of light of the medium (atmosphere walls, vacuum, etc.), and electricity travels through copper at about 2/3 of the speed of light in a vacuum.

That is really peripheral to how fast data is transferred in a network. For example, you could transfer data at 100 Mbps, 1 Gbps, etc. through copper, fiber, or radio.

There is a lot more involved in how fast you can transfer data, and it is a subject far too large to be discussed here.

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    Copper transmission is no worse than 2/3 the speed of light in a vacuum (over 200 million meters/sec). Fiber is slightly faster although the light path distance is longer than the cable distance (as light bounces between the jackets in a fiber cable). Jan 5, 2016 at 23:53
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    Right, but light doesn't need to charge the fiber capacitance up and down before the signal can be sent to the other end the way electricity does for copper. I mis-typed, and I will correct it. My point is that in networking in a business environment (the focus of this site), the transfer of data isn't completely affected by the medium over which it travels.
    – Ron Maupin
    Jan 6, 2016 at 0:10
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    @Everton, a signal may get from point A to point B faster, but that really doesn't play a part in the network data transfer rate until the data transfer rate approaches the theoretical limit of the medium. For instance, ethernet on copper can transfer data at 10, 100, 1,000, and 10,000 Mbps, but the electricity still travels over the copper at the same speed for all those data transfer rates. The speed of electricity in copper is not the limiting factor in ethernet data transfer rates. The same holds true for Wi-Fi.
    – Ron Maupin
    Jan 6, 2016 at 3:56
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    @Everton, over a significant distance (which Wi-Fi doesn't do), there could be a latency difference, but it is dwarfed by the latency required for serialization/deserialization, buffering, encapsulation/decapsulation, etc. The difference in end-to-end speed of various media at the current maximum data rates is basically swallowed by other problems.
    – Ron Maupin
    Jan 6, 2016 at 4:54
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    @Everton: HFT definitely cares more about latency than throughput, so this kind of thing matters (and the related regulations that try to level the playing field), but wireless would never be an option - the jitter of wireless connections is completely untenable, and even if not the possibility for your competitors to interfere with you is just too great. Jan 6, 2016 at 9:50

Wireless communication (especially cellular) is slower due to errors probability which is much higher than wired. It really depends on many parameters such as signal strength of the base station. In some cases cellular networks can easily add delay of few seconds.

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