# 5 volts; 1,000,000 amps

Is that possible?

Could it hurt you?

Would it get hot? Could you feed off of it with dinky little wires?
edit: I realize it’s inefficient and impractical… I’m only asking about feasibility.

It’s certainly likely that it’d kill you. 2 Amps is enough to kill you. There’s a device called the N-machine that’s a bit of a curiosity, IIRC. It produces almost no volts, but a tremendous amount of amps. I don’t know if you could get 5 volts at a million amps, but if you could, and you got hit with it, I don’t see how you could survive.

1.In theory, yes, but quite impractical. The ohmic resistance is 5V/1 Meg A = 5 µΩ.

2.There isn’t a proper way to answer this; no part of your body has that high of conductivity, so you can’t actually produce those particular values. Putting 5V directly on most parts of the body won’t hurt you, no matter how much current is ‘available’. You can put this on your tongue, and it’ll give you a little sting (a 9V battery is quite noticeable). I’m not sure what the resistance of an exposed heart might be, which is probably the only place 5V might do some damage.

3.Using wires, you’d need very large wires to get the resistance that low. Small wires simply wouldn’t yield those two values. Putting 5V (or 1 Meg A) into a short small copper wire, with ‘infinite’ available current/voltage, would burn up the wires due to heating in them.

By specifying both voltage and current, you’ve implicitly specified the ohmic resistance. 5V at 1 MegaAmp is not something you can ‘force’ onto a circuit; you can really only force current or voltage. Power supplies may often be specified with two values; that merely indicates the maximum possible, not what is produced in every case.

To amend my statement on ‘hurting you’. I should have mentioned that 5V on the heart would likely kill you, though I figured an exposed heart is kind of a problem already. Nevertheless, I must clarify the bit about ‘on the body’, in light of this Darwin award. Puncturing the skin and sending the current straight across the heart via the moist internal tissue & blood is enough to kill you, even at low voltages (the reference award winner died at 9V from finger to finger). A small amount of current on the heart will kill you; a larger amount may well do the same and will most likely burn you.

I also didn’t mention it, but if you could apply an ideal current source of 1000000A to most body parts it would burn them in the same way as the copper wire burned up.

Correction : the Darwin award is unverified, but the story is plausible.
Human internal resistance is on the order of a few hundred to one thousand ohms, and sending a current of a few tens of mA (quite possible at 5-10V) into the heart can cause fibrillation, which is often fatal. A larger jolt of current can stop the heart (and it may start up again; this is how a defibrillator works - it shocks the heart to stop it and get it working properly).

Yes.

If you are made of a substance that is almost, but not quite, entirely unlike a superconductor.

In electroplating plant and anodising processes you do get low voltages and extremely high currents, not as low as 5 volts, and the currents are in the thousands rather than the millions.

I’ve seen this in a company that made parts for the printing industry.

I don’t recall the figures but was told while I was there that the Swedish railways run on a very low voltage and high currents.

So if I’m entirely like a superconductor, I don’t have to worry. Check.
And if I’m not at all like a superconductor, I don’t have to worry. Check.

edit: Wait… your fancy jargon has confounded me. I AM almost entirely unlike a superconductor!

There is no direct evidence that this actually happened. Note that the Award remains unconfirmed.

I missed the edit window trying to find a solid number on the conductivity of blood & muscle, but I did issue a correction in post 5. Looking at it again, I doubt it actually happened as described (I was fighting insomnia while posting last night).

The smelly thing about the electrocution story is that you don’t expect a resistance measurement probe to provide enough current to kill you. But if you did wire a 9V battery into subcutaneous connections in opposite hands, or anywhere that crosses the heart, you’re risking death.

I’m not sure that I would call 15000 Volts AC “very low”.

It is, however, lower than the 25kV AC used by Denmark; this is an issue because the two networks are connected by the Oresund bridge. (I’m guessing that this is what your informant meant by “lower voltage” in Sweden.)

I am not going to argue if this is true, or not, but I do want to point out that even though a DVOM is powered by a 9V battery it does not put anything like 9V out to the probes when measuring resistance. Typically a DVOM will put between about .6-.75VDc into the circuit to measure resistance.
I used to have my students take two DVOMs one set to voltage, the other to resistance to show to them why you don’t use an ohmmeter to measure the resistance of an airbag. :eek:

With the exception of very high resistance ranges, high quality DVMs limit the excitation voltage to around 0.5 V when measuring resistance. It’s not for safety. It’s to prevent forward biasing silicon semiconductors when measuring the resistance of a resistor “in circuit.”

Essentially what you’re suggesting is a current source that can produce 1,000,000 amps. (Once you have this current source, you can create 5 V by using a copper bar with the correct geometry.) I don’t think anyone has made a current source that can produce a continuous current of 1,000,000 amps. (Best I could find was a supply that can deliver 40,400 A into a super conductor.)

Current sources can be quite dangerous in the lab. As an example, let’s say you adjust a current source to produce 0.1 A DC. If you touch across its terminals, it will keep ramping up the current until 0.1 A DC is produced (or the compliance voltage is reached). This can kill you. But I have a feeling this is not what you’re asking.

If you’re asking, “If I have a current source that can produce 1,000,000 A, and it has a compliance voltage of 5 V, will it hurt me if I touch across its terminals?” the answer is, “Probably not.” The current will simply ramp up until 5 V is reached. The final current will probably be less than 0.5 mA.

If you’re asking, “If I have a current source that can produce 1,000,000 A, and I place a copper bar across it so that 1,000,000 A flows through the bar and 5 V is produced across the bar, will it hurt me if I touch across the bar?” the answer is, “Maybe.” It’s not because of the voltage; generally speaking, 5 V won’t hurt you. And it’s not because of the current; the current is flowing through the bar, not you. So why did I say “Maybe?” Because the copper bar will be dissipating 5,000,000 W of heat. Unless the bar has an extremely effective cooling system (e.g. a massive, closed-loop, liquid cooling system), the bar will be very hot, and you’ll burn yourself when you touch it.

Dinky wires? Nope. Hot? Yea, the supply will generate a lot of heat. In addition to the copper bar across the terminals, you’ll also need a massive, closed-loop, liquid cooling system for the current source.

I know you meant voltage here, not current.

Eleusis, what you may be getting from everyone here, but isn’t expressed quite this way, is…

Yes, you can put 5 volts across any resistance, like the human body. But the amount of current that will flow is limited by (1) the value of the resistance, and (2) the capability of the supply source. If you have a high resistance, only a small current will flow. If you have a low resistance, the supply would have to be capable of providing a large amount of current for any large amount to actually flow.

And, of course, tiny wires won’t carry much current without heating and/or melting, which might be a moot point; you might melt first.

Also, 5v @ 1MegaA is 5MW - my house is wired for 48,000W, so you’re talking about a subdivision’s worth of power…

If you are interested in this sort of thing, there’s an ancient book “Magnetism” by E.W. Lee (published in 1963), with photos of a solenoid that is fed directly by a huge generator - the entire output (170v @10,000A) is fed into this coffee-can sized coil to generate giant magnetic fields. The coil is cooled by water flowing through firehoses.

All I can tell you is that if you take two Fluke 78s set one to DCV and the other to ohms, you will read about .6 or a tad more on the voltage scale. These are 10Megaohm impedance units.