Shoutbox

I know the amps will kill you not volts.

Which hurts though?

amps

More info: http://en.wikipedia.org/wiki/Electric_shock

You don't usually have one without the other. Given that contact resistance is pretty much always in a certain range, or better yet, negating contact resistance and measuring from within the skin, you get pretty much ohmic behaviour, ie, a constant relationship between voltage and current. So from that perspective, one is not worse than the other.

And of course ultimately, the thing that really does damage is power, and the amount of damage done depends on the time, so you have three important factors.

Well, both can hurt, but i'm pretty sure what you're going to feel ultimately is the voltage, which is why tazers use thousands of volts and minuscule amounts of amperage. However, it doesn't take much amperage across the heart to kill you.

Both, you never get one without the other. Volts are what hurt though, I'd imagine, as the power grid lines are all extremely high voltages(The voltage is stepped up through transformers upon leaving the power station and then stepped back down on the other end) and as you know, power lines hurt like a bitch and pretty much always kill you. Also, if you think about it, all signs say "Caution: High Voltage" etc, never "Caution: High Amperage"

It's not especially the fact that a wall socket is 230V (or 115V for whoever else) that kills you, it's that it operates AC at 50Hz. 230V at a maximum of 13A (30A if you just get two metal prongs, jam them into the socket and then touch them both) is more than enough to cross into the human body.

[Note here: I think the voltage is a constant 230V, the current [amps] goes down dependant on the resistance in the circuit, ie, your body.]

But the 50Hz going through your body causes your heart to fiblirate (ie try to beat 50 times per second, which it fails miserably at). That's why you can use a defiblirator (you know, those paddle things you seen in ER, etc.) to help a person that's had an electric shock from a wall socket.

Substations and the like can have 10k-250kV running through them, that just burns you to cinders.

[The way to think about current and voltage is like a pump pushing water through a pipe. The voltage is how hard the pump is pumping, and the current is how much water is actually flowing. Using the same pump to pump through a small pipe (high resistance) will mean less current flows through the pipe, whereas if there was a big pipe there would be more water flowing - more current - due to a lower resistance].

Does that cover it?

what about if it's DC, not AC?

What you mean like sticking a 9V battery on yer tongue?

It's the current. Sort of. For example, a 9V battery should always put out 9V. So, stick the 9V battery against yer tongue, OUCH. Cause your tongue is wet, it has less resistance, hence a bigger current.

Put your finger across it, nothing happens, because your skin has a much larger resistance.

quote:

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Originally posted by andrewdodd13
It's the current. Sort of. For example, a 9V battery should always put out 9V. So, stick the 9V battery against yer tongue, OUCH. Cause your tongue is wet, it has less resistance, hence a bigger current.

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And here is my point about measurement. Because dead skin has a high resistance, touching your finger to a battery is like putting a pair of 10k ohm resistors in series with the battery. So, the voltage across the live skin is also significantly lower! For example, if the muscle between the terminals has a resistance of 10k ohm as well, you're only getting 3v across the muscle. Of course, the current is lower as well, and so the total power through live cells when you touch a battery to your skin is 1/9th what it is on the tongue.

You also have factors like internal resistance, and when dealing with batteries, K values of the chemical reaction, which serve to complicate things.

quote:

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Originally posted by andrewdodd13
What you mean like sticking a 9V battery on yer tongue?

It's the current. Sort of. For example, a 9V battery should always put out 9V. So, stick the 9V battery against yer tongue, OUCH. Cause your tongue is wet, it has less resistance, hence a bigger current.

Put your finger across it, nothing happens, because your skin has a much larger resistance.

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A 9 volt battery doesn't always put out 9 volts. If it's being asked to deliver a lot of power (which it can't) the voltage will be depressed.