I have encountered several articles and posts saying that what electrocute you and cause death is actually not the voltage but the current instead but is not clear to me how this works.
In: Physics
Voltage and current are related in the form voltage=current*resistance
So to have a high current tour a human you need high voltage too. What is really dangerous to you is the energy delivery to you that is voltage*current*time. Something with high voltage can drop quickly when you short it like in a static discharge, Then you have high current and high voltage but a fraction of seconds and very little energy.
The confusion is because it is quite easy to get a high voltage like with static electricity and measure it when nothing is connected to it. The problem is that holds very little charge and when the electrons start to pass trough you the voltage drops quickly.
Current is measured when it flows so measure it harder because in static discharge it might be a million of a second long
So you have a high voltage over you a high current trough you for a very short time and the energy it can deliver is so low that is does not damage you.
so any demonstration that shows that high voltage is not dangerous the voltage will drop when a human touches the device.
If the thing you touch has is not a static charge but a part of the power grid the voltage will remain high when you touch it and therefore a high current and a lot of energy deliver trough you and you are likely killed.
It is not possible to deliver high current at low voltage Look at [this video](https://www.youtube.com/watch?v=XDf2nhfxVzg) by electoBOOOM with a 20V 150A power supply that you can use to weld metal because of the low resistance in the metal. But he does it with one the positive electrons in one hand and the negative in the other. So the voltage is so low that the current and therefore the energy delivered to a human is negligible.
So it is cleat that something that can deliver a high current is not dangerous is the voltage is low enough.
Both the voltage over the source and the current it can deliver over time is what determine danger.
This is [another video](https://www.youtube.com/watch?v=DOMs7mYm_zs) from ElectroBOOM on the same subject. It end in the following
>It is not necessarily a supply voltage at no load, ut the amount of current it can provide when touched that indicates how much hurting you shall receive.
Because a touched supply voltage may drop if its current is somehow limited.
There is a reason you have “high voltage” warning signs not high “high current”. The high sustained voltage will kill you because it results in a high sustained current.
High current and lowe voltage trough a human is not possible because we have quite high resistance, voltage=current*resistance
Ohm’s law says that voltage is equal to current times resistance. Saying “it’s the current that kills” is very misleading because you cannot have lethal current through your body without lethal voltage driving it.
The reason this myth gets spread is because there are many high voltage sources that cannot supply enough current for long enough to kill you. Take a static shock for example. Let’s say a doorknob and your finger have 1000 volts between them. You go to touch the doorknob and get shocked. The shock happens and the voltage between the doorknob and your finger drops to zero almost instantly. If there were a power supply keeping the doorknob at 1000 volts you would be dead.
Wait, the doorknob was at 1000V and it didn’t kill you! But the doorknob was only at 1000V for a fraction of a millisecond and the average power was minuscule.
Current and voltage are related and both kill. However, some sources don’t have the required power to kill you.
It’s more, the overall power.
Power is measured in Watts, and it’s voltage (volts) x current (amps)
Tasers, often use thousands of volts, but at very low current. They hurt, but they’re very rarely lethal. So it’s assumed that volts don’t kill.
Current, on its own, can’t kill you either.
If you touched something that can deliver 1000 A, but there’s only 0.1V there, it probably won’t even travel through you.
You need Voltage to push current through anything, since everything has resistance.
So you need both, a high enough voltage, and a high enough current. With enough of both, you’ll cook.
You are not a good electrical conductor. You’ve got a lot of resistance, so it takes a lot of voltage to run any current through you. Plus, you are mildly resistant to electricity, so a shock might startle you but it won’t harm you unless the source can provide enough voltage to run electricity through you **AND** at enough current to harm you. When you reach out to a doorknob and there is a spark, that’s a lot of static electric voltage, but not enough current to harm you. Touching that much voltage from a power plant, which can provide hundreds of amps of current, will electrocute you.
Think of a ball rolling down a hill. More “voltage” is a steeper hill, so the ball will roll faster and have a higher speed at the bottom of the hill. “Voltage” is how much force is actually behind the flow of electrons. With enough force, it can create huge sparks – the most spectacular being lightning. The force can jump huge distances!
A bowling ball rolling down a steep hill is something you likely don’t want to get in front of. But a small marble rolling down that same hill at the same speed can just be blocked with your foot. That’s current – basically the amount of force behind the current. A tiny bit of force with a huge current tends to get spent very quickly, but can easily pass through you. This is how tazers and electric fences work – they give brief pulses of high voltages that hurt like hell.
The total amount of energy (called “power”) would then be analogous to the speed of the ball at the bottom of that hill, combined with the weight of the ball itself. A very low voltage with high current would be like you holding a bowling ball in place with your foot as it was trying to roll down a light incline. You’d feel a light nudge as you stop it, but it wouldn’t hurt. However, that same ball going down a steep hill could well smash through a small wall at the bottom, if it picked up enough speed.
* What *actually* kills you are the electrons burning up your flesh and vital organs.
* Voltage is like the amount of pressure being put on those electrons.
* The higher the pressure, the more likely they will flow through you body and burn you to death.
* However current is very much like a measure of how many electrons are flowing per second through you.
* So if there is a high current then by definition there are lots of electrons flowing through you and burning you.
* So you can have a high voltage but if there are only a very small number of electrons at that high voltage, then they won’t do much damage.
Electricity kills in two ways: gross physical burns, and disruption of the autonomic nervous system. If you happen to be, say, struck by lightning, then odds are good that you die from having large bits of you incinerated. If you are electrocuted by, say, the electric chair, they will run about two thousand volts to punch a a dozen amps through your brain, spine and heart. The trick is that the sack of skin around you isn’t really a good conductor, and there’s a lot of other insulating and dissipative factors between your nerves and the outside of your body, but if you can get as few as a couple of hundred milliamps directly applied to the heart you can disrupt its operation. That was how the first defibrillator was proven, with open heart surgery and conductive pads. As to why, that’s just a feature of biology. The nervous system is just more reactive to amperage.
Voltage is a ratio. Using the water analogy of electricity, it’s not the speed water flows, and it’s not quite like pressure, because it doesn’t imply there’s a push or pull behind it. Instead, think of it as a river; and since water flows downhill, think of voltage as the decline, the slope, which can be expressed as a ratio. Water has more propensity to flow down a hill with more slope and regardless how much water is behind it, so it makes for a better analogy than the classic pressure analogy. And when voltage drops, that slope decreases, flattens out.
Amperage is current. The classic analogy kind of works well. How wide is that river? Imagining a cross-section of a larger river, all flowing down a slope is pretty good. Once again, don’t concentrate on the water behind this imaginary cross-section, don’t concentrate on the slope, we’re only talking about the cross-section itself, the area. What makes it terrifying is imagine using your body to stop a garden hose of water. There’s only so much voltage so water is just spilling out the front, and it’s about 3/4″ wide. You get wet. Now imagine using your body to stop the Nile river at the same voltage. Yeah, the water ain’t flowing all that hard, but first we have to flatten you out into a sheet that spans the river, and assuming you were made of plastic and we could do that, what chance do you think you have of stopping or redirecting that current?
It would only take a few milliwatts to kill you. You don’t need a lot of voltage or amperage. What typically saves you is when you get electrocuted, the electrical path THROUGH your body doesn’t bridge your brain or your heart, where it can do some real damage. You don’t need to kill cells by frying them, which would happen because as a human resistor, wattage would be converted into waste heat – the atoms and molecules in your body would act as a load and convert some of that electrical energy and your atoms would get excited – heat. It would be enough to break bonds and disrupt chemical processes. No, you don’t need to kill the cells, you would just need to disrupt vital cellular and bodily functions. Throw your heart into an atithmeia, and you’d die of essentially a heart attack.
So it’s no one thing about electricity that kills you. It’s current, it’s voltage, it’s time – as a high wattage shock over a short time can kill you as some low wattage shocks over a long time.
Voltage is the potential for charges to flow with a given energy. Current is actually how much charge is flowing per second.
So straight from the definitions, we see that current is quite literally the moving charges that could kill. Now for the metaphor…
Say you’re at the base of a skyscraper, and I’m on the roof. I have a very high potential to throw deadly bricks at you. That’s voltage. Voltage on its own doesn’t imply a current.
If you give me access to only a few bricks, that wouldn’t amount to shower of brick death. If you gave me access to ceaseless truckload of bricks, you’d probably die. That’s current.
Think of electricity like poisonous water moving in a river. Current is kinda like how fast the water is going, and voltage would be kinda like how much pressure the water has on the dam upstream. It is like more potential energy. Let’s say you try to cross the river. A high current would mean their is more toxic water passing over you, so you get sicker, and are more likely to be killed. But it can also depend on things like if you are wearing protective clothing. Even if the voltage/pressure of the water of the water behind the dam is high, as long as the resistance of the dam is strong, it won’t affect you.
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