85 points

When the battery connected:

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1 point
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66 points
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An AAAA cell has 200-350 mohms internal resistance. A 9v battery has 6 of them in series (many of them are literally that, others have their cells as a stack of plastic buckets). The nose ring is a short run of wire, it’s idunno a 0.2 ohm heater?

I think the septum is going to get pretty toasty.

https://data.energizer.com/pdfs/e96.pdf

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56 points
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I just tested this (for science!) with a 9V battery and an iron nail of roughly nose-ring diameter. Both the nail and the battery get unpleasantly hot after several seconds. I don’t think they’d get hot enough to burn you, though. (Don’t take my word, though, please!) I believe the internal resistance of the battery does also increase with the temperature, so it effectively somewhat self regulates itself.

Common nose ring materials like Titanium and Stainless Steel are 4× and 7× more resistant than iron, which means they should dissipate more power than the nail, and thus get hotter. I was calculating something around 3 milliohms for a titanium 16 gauge 10mm wire, and 0.7 milliohms for an iron wire.

Regardless of material, at 1000 milliohms internal resistance, i think the battery itself is doing most of the heat dissipation. (But also over a much bigger surface area!)

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12 points

How long did you keep the nail on the battery for?

A 9V battery can be used as a foam cutter.

Styrofoam and most art foams melt at about 200°C

https://youtu.be/4Hj9PJstexk?si=_NEMZZU4Yu_CSN0a

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9 points
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About 10-20s, I left it on until it didn’t seem to be getting much hotter. I also didn’t want the battery to overheat and fail catastrophically. I think because the “wire” is such a large gauge, there’s not enough current for it to get seriously hot. In a foam cutter, you’re passing all that current through a much smaller cross-sectional area.

Edit: just to confirm, I did a little math. A 10cm steel wire with a tenth of the diameter would have a resistance of 5 ohms. That means that instead of 1% of the total heat dissipating in the thick wire, 80% of the heat is dissipating in the wire in foam cutter’s case, and there’s more total resistance, so more heat dissipation as well.

This is because:

A = π r²

R = ρ × L / A

So resistance is proportional to the material resistivity (ρ), the length (L), and the inverse square of the radius (r⁻²). That is to say, decreasing the radius by a factor of 10 increases resistance by a factor of 100.

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1 point

Here is an alternative Piped link(s):

https://piped.video/4Hj9PJstexk?si=_NEMZZU4Yu_CSN0a

Piped is a privacy-respecting open-source alternative frontend to YouTube.

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10 points

/c/theydidthescience

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9 points

Thank you for your service

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1 point
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27 points

Well now I want to try this with my septum piercing and find out

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52 points

Do it with the piercing OUT OF YOUR BODY. You don’t want a hot piece of metal that you can’t get off of yourself fast enough.

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22 points

You could put one in a hot dog and shock it if you want to try it without making your nose toasty

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5 points

If you do please let me know what happens lol.

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50 points

Wakey wakey, septum bakey

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26 points

Would the person feel anything? Presumably the electricity would flow through the metal as path of least resistance?

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83 points

You don’t shock the person.

You heat up the metal until it burns them.

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17 points

I used to burn paper with a 9 volt and a paperclip. Good times

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34 points

It’s a short, the metal would heat up extremely fast and burn.

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-5 points
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10 points

Why would you spread incorrect information so confidently? You’re absolutely wrong. A 9 volt will get hot in a few seconds when shorted.

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10 points

You can start a fire with a 9v battery and some steel wool.

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6 points

Put an AA battery in some aluminium foil, much can happen with even such a small battery

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5 points

I mean, someone with a septum piercing could confirm this pretty fast.

Pretty sure it would be nice and toasty inside 30 seconds.

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26 points

Yes, it would heat up. It would not be pleasant

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11 points

They prob wouldn’t get shocked but the ring and battery will get very hot very quick as there i pretty much no resistance wich means there is a lot of current flowing.

Someone else in the comments claimed to have calculated a resistance of 0.2 ohms.

I=U÷R

9V ÷ 0.2Ω = 45A

45 amps is a lot of current to flow through a nose ring. I don’t know how much that is in heat but i’d expect you to get burned from it

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9 points
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You won’t get more than a few mA out of an alkaline, but heat does build up. (Internal resistance)

A NiMH on the other and can give over 10 amps. They’re a seriously risky thing to leave around loose metal bits. Or attached to thin wires.

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7 points

Definitely won’t get shocked. I’ve run estim through nipple piercings and no shocks

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6 points

Just put a 9volt in your pocket with some change

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-25 points

No, 9v batteries have almost no shock to them. Put one on your tongue or lick your finger and touch the terminals. You’ll feel nothing.

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41 points

Dry skin is hundreds of thousands of ohms. Even wet skin has pretty good resistance. When you touch a 9v to your tongue, you’re starting to mess around with lower resistance flesh, it is definitely not a comfortable thing to do.

The metal ring doesn’t do anything to move more electricity into your body, but it soaks every electron the battery can push and turns it into heat. Best I can figure it would amount to a few watts, which would be toasty if you were holding it between your fingers. The septum is a thin piece of flesh, I think it would sauté pretty quickly.

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11 points

Thank you, I appreciate the explanation. Being fairly physics ignorant I was wondering about that.

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29 points

I mean, if you lick a 9v you definitely feel something. It’s not painful, but it’s not natural or pleasant either.

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6 points

Can confirm. Used to lick them as a kid

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2 points

If those are separate pieces of metal embedded in the skin, they will feel something. If it’s just an incomplete ring, it will draw so much current that the battery voltage drops too low to feel anything but the heat.

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17 points

Another confidently incorrect person

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What? They are clearly just screwing around man.

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-2 points

Woosh I guess

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6 points
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But it’d probably get really hot

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1 point
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12 points

You’re doing it wrong. You gotta place a metal sphere close to it connected to a Van de Graaff generator.

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