If electricity is faster than the speed of sound why does it not make a sonic boom?
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even large electrical currents don’t have enough mass to really push the air out of the way. Without the ability to displace a lot of air quickly, no sonic boom can be created.
So first of all, the actual electron movement is fairly slow, only a few cm a second. The reason power travels through a cable really quickly is that if the first electron moving pushes the second forward pushes the third forward and so forth.
Just like when you take a stick, even if you move the stick slowly, the end opposite to the one you’re holding starts moving (almost) instantly as you move it.
Secondly, the electrons travel through copper wire not through air. The speed of sound in copper is several times higher than that in air.
Thirdly, a sonic boom is created through fluid dynamic effects, it simply doesn’t exist in solid materials.
Fourthly, something as small as an electron is not capable of creating the pressure interactions for a sonic boom
It does. When lightning strikes. When the bolt of lightning moves through the air, it superheats it. The result is the air expands faster than the speed of sound and infact, millions of sonic booms are created, it is what we hear as thunder.
When you see something like a huge van de Graaf generator throwing huge arcing bolts of electricity, there are still sonic booms being created – it is what you hear when it crackles, however electricity has no mass as it is a form of energy and not matter. The crackles you hear are from the air expanding faster than sound, but because the electrical bolt is small it doesn’t elicit a big boom.
However when you look at *massive* objects, as in objects that have mass and are made of matter, then a sonic boom is different. It is literally the object travelling faster than the speed of sound and the sound barrier is literally broken, the air moves repeatedly from the front of the vehicle to the rear in an extremely violent event which creates the “boom” sound you hear.
The electrons themselves aren’t moving very fast. The speed at which electrons influence each other is what’s close to the speed of light. It’s sort of like the speed of sound vs the speed of wind.
Even if they were moving that fast, you don’t get a sonic boom unless the air is being pushed out of the way to make space for the object passing through it. Electricity doesn’t push air out of the way like that. With lightning what happens is the voltage gets high enough to tear electrons off of the air molecules, and when there are electrons floating around unattached to a molecule, the material becomes conductive. The electrons are still at close to the same density they were before, they’re just mobile now. With lighting, it’s just enough electricity flowing at once to heat the air a lot, and that hot air expands shoving other air out of the way, creating thunder.
My last comment was removed so I will explain further, thunder is a sonic boom from unimpeded electricity moving faster than the speed of sound. Electricity has impedance within circuits, regulators, that do not blow the circuits
Isn’t it the air collapsing back into the space created by expanding air after a lighting strike that makes the sounds?
Electricity doesn’t displace air, therefore no boom?
When it travels through air, you essentially get a sonic boom, aka thunder.
While traveling through a conductor (wires) it isn’t displacing or effecting the air that surrounds it.
Electrons have very little mass, when you have a big power surge, such as lightning striking, it does create a boom and you get thunder. It’s just not that same boom created by an object with mass moving very fast.
Normal electricity isn’t moving by pushing atoms aside. It’s moving through the space “between” atoms. Nothing is getting displaced, so no sonic boom opportunity. The electrons themselves also aren’t going very fast (the electric *field* moves very fast…speed of light fast…but it has no mass and doesn’t displace anything).
Lots of thunder references here…that’s not a sonic boom from the electricity. The electricity in a lightning bolt isn’t going that fast. But it superheats the air, which tries to expand really fast, and that moving air *is* trying to go fast and shove air out of the way. That’s a conventional air-in-air sonic boom, like a jet exhaust, that’s powered by the electricity.
Electricity is not faster than the speed of sound. Electrons move at a few cm per second.
Current in a wire created by a voltage source is like water flowing through a hose pushed by a pump. The water/electrons get pushed through the pipe/wire at a fairly slow speed, but all the water/electrons in the pipe get pushed at the same time.
So, when you flip on a light switch the light turns on instantly, but it’s the electrons that were already at the light that are causing the light to turn on, not the electrons that were at the switch when you flipped it. They won’t arrive at the light for many seconds or even minutes, depending on how long the circuit is.
In other words, unlike the common misconception, electrons don’t carry power from a power source to the destination and then have to go back to get “charged up”.
EDIT: Some more important detail: Only in a DC circuit will electrons actually travel around the circuit in a loop. In an AC circuit, like used in homes, the electrons get pushed one way then the other (changing directions 50 or 60 times a second typically) endlessly. Much like if you had a reversable pump that would pump water one way then the other endlessly in the hose.
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