What voltage and amps are and why high volts may not kill you but high amps will
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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.
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