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

[–] Enkers@sh.itjust.works 53 points 11 months ago* (last edited 11 months ago) (4 children)

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!)

[–] Shard@lemmy.world 11 points 11 months ago (2 children)

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

[–] Enkers@sh.itjust.works 9 points 11 months ago* (last edited 11 months ago)

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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[–] Akasazh@feddit.nl 10 points 11 months ago

/c/theydidthescience

[–] machinaeZER0@lemm.ee 9 points 11 months ago

Thank you for your service

[–] lone_faerie@lemmy.blahaj.zone 26 points 11 months ago (3 children)

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

[–] rotopenguin@infosec.pub 51 points 11 months ago

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.

[–] Angry_Maple@sh.itjust.works 21 points 11 months ago

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

[–] Onaltau@lemm.ee 4 points 11 months ago

If you do please let me know what happens lol.

[–] Aurenkin@sh.itjust.works 49 points 11 months ago

Wakey wakey, septum bakey

[–] Dave@lemmy.nz 25 points 11 months ago (6 children)

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

[–] Melkath@kbin.social 82 points 11 months ago (1 children)

You don't shock the person.

You heat up the metal until it burns them.

[–] 0ops@lemm.ee 16 points 11 months ago

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

[–] toxic_cloud@lemmy.world 33 points 11 months ago (1 children)

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

[–] TrickDacy@lemmy.world 25 points 11 months ago

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

[–] SaltyIceteaMaker@lemmy.ml 11 points 11 months ago (2 children)

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

[–] XTL@sopuli.xyz 9 points 11 months ago* (last edited 11 months ago)

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.

[–] captainlezbian@lemmy.world 7 points 11 months ago

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

[–] Hikermick@lemmy.world 6 points 11 months ago

Just put a 9volt in your pocket with some change

[–] TimeSquirrel@kbin.social 11 points 11 months ago

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

[–] AlexJD@feddit.uk 9 points 11 months ago

Cursed welding

[–] Omega_Haxors@lemmy.ml -3 points 11 months ago (1 children)

How many times is this reddit tier meme going to be reposted here??

[–] Uniquitous@lemmy.one 1 points 11 months ago (1 children)

Until people stop bitching about reposts.

[–] Omega_Haxors@lemmy.ml -5 points 11 months ago (1 children)

Reddit tier comment.

[–] Akasazh@feddit.nl 2 points 11 months ago (1 children)

Then go back, we don't care.

[–] Omega_Haxors@lemmy.ml 0 points 11 months ago

Good idea, then I can see nothing BUT that kind of shit.