What voltage and amps are and why high volts may not kill you but high amps will
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Water makes a decent analogy, pressure is voltage, flow rate is current(amps). It takes a certain amount of current flowing through your body to kill you, but you can’t get that current without having enough voltage to overcome the resistance of your skin and flesh.
Water significantly reduces the resistance of your skin, allowing lower voltages to push harmful levels of current through your body.
Though it’s more complicated than I’ve just described, especially when you start considering AC of different frequencies.
Water makes a decent analogy, pressure is voltage, flow rate is current(amps). It takes a certain amount of current flowing through your body to kill you, but you can’t get that current without having enough voltage to overcome the resistance of your skin and flesh.
Water significantly reduces the resistance of your skin, allowing lower voltages to push harmful levels of current through your body.
Though it’s more complicated than I’ve just described, especially when you start considering AC of different frequencies.
Volts is the potential that causes charges to move. And current is the amount of charge that is moving. People frequently use the water analogy where volts is the pressure of a hose, and the current is the flow of the water going through the hose.
You need both to kill you since it is the energy transfer that kills you and energy is the product of volts, current, and time.
A high voltage with no current won’t cause you many issues. You experience this with the zap from static electricity. This is extremely high voltage (thousands to millions of volts), but hardly any power is delivered since the current dissipates very quickly and the voltage drops just as quickly.
If you have a current flowing through you, then that means you have enough voltage to make that current flow. Humans skin is relatively high resistance 1k to 100k depending on dryness, so to get appreciable current you have appreciable voltage and appreciable power. 10mA current can give nasty shocks, and 100 to 200mA is generally considered fatal. Even if not fatal, electrical current will cause heat in the body and can damage tissues.
The water analogy is best. Voltage is pressure, current is flow.
If you have one of those nozzles that you can turn to adjust the flow out of your garden hose, when you make it tight and it sprays a mist, that is high voltage, low current.
When you open it out so the water just glubs out of the hose, that is high current low voltage.
A firehose would be doing both high current and high voltage.
Volts and amps are related by ohms law:
Volts = amps × resistance
If you assume a constant resistance of the human body, then the volts must be sufficiently high to push enough current to be fatal. Thus, the expression “it’s the amps that kill you” is nonsensical.
However, resistance is not constant through the body (to be clear, I’m not saying that the individual tissues have different resistances, of course that is true. What I mean is that the resistance through the body from input to output, even when taken as a whole, is not constant). Something happens in the human body when the voltage reaches a certain threshold. The skin resists electricity up until the electric field of ever increasing voltage causes the electrons of the atoms in your body to all move away from the electric field while leaving the protons close to the field. This makes the molecule polar and more conductive. This phenomenon is called dielectric breakdown.
When that happens, the resistance through your body becomes much lower and, per ohms law, a smaller voltage produces a larger current.
Water makes a decent analogy, pressure is voltage, flow rate is current(amps). It takes a certain amount of current flowing through your body to kill you, but you can’t get that current without having enough voltage to overcome the resistance of your skin and flesh.
Water significantly reduces the resistance of your skin, allowing lower voltages to push harmful levels of current through your body.
Though it’s more complicated than I’ve just described, especially when you start considering AC of different frequencies.
Remember that current = voltage divided by resistance.
High current may kill, but high current is caused by high voltage and/or low resistance. __Current is the actual flow of electricity, which is why we say it’s the dangerous part__, but these other two factors are very much related to current. You can’t have high current independently of the other two factors.
It doesn’t take that much current to kill you. Somewhere in the neighborhood of 50mA can stop your heart, which uses its own (smaller) currents to operate. That’s 0.05 Amps.
The resistance of your body tends to be pretty high, so it often does take fairly high voltage to generate that 50mA+ current through your heart, unless you’re stabbing the wires directly into your chest.
The resistance of your body varies a *LOT* though, depending on things like how moist your skin is, and which part of your body touches the wires. If you find a particularly low resistance path to your heart, a not-so-high voltage can still generate a lethal amount of current. So be careful, regardless of the voltage you’re working with!
Volts is the potential that causes charges to move. And current is the amount of charge that is moving. People frequently use the water analogy where volts is the pressure of a hose, and the current is the flow of the water going through the hose.
You need both to kill you since it is the energy transfer that kills you and energy is the product of volts, current, and time.
A high voltage with no current won’t cause you many issues. You experience this with the zap from static electricity. This is extremely high voltage (thousands to millions of volts), but hardly any power is delivered since the current dissipates very quickly and the voltage drops just as quickly.
If you have a current flowing through you, then that means you have enough voltage to make that current flow. Humans skin is relatively high resistance 1k to 100k depending on dryness, so to get appreciable current you have appreciable voltage and appreciable power. 10mA current can give nasty shocks, and 100 to 200mA is generally considered fatal. Even if not fatal, electrical current will cause heat in the body and can damage tissues.
It is a bit complex for some people.but.
0.1A of current through your hart can kill some people. So yes. current kills.
But
Current does not want to go through your hart. It is not lurking to jump at you. It wants to run off in million directions and will take the easiest path. It must be forced through you with no better way to go to be dangerous. The “force” that moves it is voltage. If voltage is high enough than it can push the current/energy through allmost anything. Pushing through you is not trivial. To push 0.1A in from your arm, through your chest, then leg and then into the ground (assuming no protective gear) can take around 1000 Volts. Most of the electronics run on 5 volts. Cars run on 24 Volts. There can be 10A going through your PC but it is not going to kill you at low voltage. There is not enough force to push. 240V in your home is relatively safe too. You can die, but you have to be unfortunate or creative. (Still, don’t poke it. Likely to survive does not mean likely to be safe or likely to be fun)
1000V with a power behind it is what kills you on touch by that calculation.
With power behind it. What does that mean?
Current is basically an amount of energy. I might raise a small battery to 1000V but a small battery runs empty in a fraction of a second, before reaching 0.1A. And so it is safe.
It is also safe to hold the metal rod at the science fair that makes your hair stand up. There is (relatively) high voltage there. More than 1000V but not enough power to kill you.
So high voltage with power behind it kills you. But then again, that just creates (deadly) current.
Disclaimer: the resistance of the human body can be different and can change depending on … Anything really. It is also important how much of the body the energy has to go through. so do not quote me on the 1000V thing. if it does not go through a hart or the brain higher currents are survivable. and in some conditions less voltage is needed. 240V in the bath is enough. So … Don’t gamble. Wear protection.
The water analogy is best. Voltage is pressure, current is flow.
If you have one of those nozzles that you can turn to adjust the flow out of your garden hose, when you make it tight and it sprays a mist, that is high voltage, low current.
When you open it out so the water just glubs out of the hose, that is high current low voltage.
A firehose would be doing both high current and high voltage.
Volts and amps are related by ohms law:
Volts = amps × resistance
If you assume a constant resistance of the human body, then the volts must be sufficiently high to push enough current to be fatal. Thus, the expression “it’s the amps that kill you” is nonsensical.
However, resistance is not constant through the body (to be clear, I’m not saying that the individual tissues have different resistances, of course that is true. What I mean is that the resistance through the body from input to output, even when taken as a whole, is not constant). Something happens in the human body when the voltage reaches a certain threshold. The skin resists electricity up until the electric field of ever increasing voltage causes the electrons of the atoms in your body to all move away from the electric field while leaving the protons close to the field. This makes the molecule polar and more conductive. This phenomenon is called dielectric breakdown.
When that happens, the resistance through your body becomes much lower and, per ohms law, a smaller voltage produces a larger current.
Remember that current = voltage divided by resistance.
High current may kill, but high current is caused by high voltage and/or low resistance. __Current is the actual flow of electricity, which is why we say it’s the dangerous part__, but these other two factors are very much related to current. You can’t have high current independently of the other two factors.
It doesn’t take that much current to kill you. Somewhere in the neighborhood of 50mA can stop your heart, which uses its own (smaller) currents to operate. That’s 0.05 Amps.
The resistance of your body tends to be pretty high, so it often does take fairly high voltage to generate that 50mA+ current through your heart, unless you’re stabbing the wires directly into your chest.
The resistance of your body varies a *LOT* though, depending on things like how moist your skin is, and which part of your body touches the wires. If you find a particularly low resistance path to your heart, a not-so-high voltage can still generate a lethal amount of current. So be careful, regardless of the voltage you’re working with!
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