xkcd #3106: Farads

Comments

• ryannathans@aussie.zone ⁨2⁩ ⁨weeks⁩ ago

  Haha that’s a good one

  Capacitors are usually in the realm of pico to micro farads

  A one farad capacitor charged to a respectable voltage would feel like a doomsday device in your hand

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  • HakFoo@lemmy.sdf.org ⁨2⁩ ⁨weeks⁩ ago

    You see low voltage ones for things like memory backup on hi-fi gear. I have some 3F/5v capacitors in an old Technics tiner.

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  • SalamenceFury@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    Wait so this is like one mistake away from turning that stickman into a fried stickman?

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    • ricecake@sh.itjust.works ⁨2⁩ ⁨weeks⁩ ago

      Depends on the voltage it’s charged with, but household current would give it more energy than a shotgun has.

      Realistically one would not do that unless you were dealing with something industrial. You would use them otherwise for things like dampening lower voltage systems that need a lot of current.

      Closer to the danger level of someone holding two exposed wires plugged into the wall.

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  • kaidezee@lemmy.ml ⁨2⁩ ⁨weeks⁩ ago

    That is why I like supercapacitors.

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  • acockworkorange@mander.xyz ⁨2⁩ ⁨weeks⁩ ago

    Worked with an industrial robot one that had 700V 0.5F electrolytic capacitors on its power supply. Those things were massive.

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    • Warl0k3@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

      I was in the building when when a 3F 1200V capacitor, part of a multi-rack mounted capacitor bank, failed. It tore the 20cm mounting bolts out of the floor, launched the three-tonne rack hard enough to crack the ceiling and shattered every window in the facility. I want to say that afterwards I never broke the rule about not being allowed to enter the experiment room until the banks were discharged, but I’d be lying. Undergrads are idiots, and holy cow don’t fuck around with those caps…

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  • DarkCloud@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    Operation Sundial 2.0, electric boogaloo.

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• ch00f@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

  I used to teach AP physics to kids on the weekends. One asked me why Farads were so big. I had to explain that there’s a fixed ratio between Farads, Volts, and Joules. One of them had to be crazy big or crazy small.

  See also Coulombs.

  Caps are especially scary because they can develop their own charge through static electricity, so large value caps are often shipped with their terminals tied together.

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  • ViatorOmnium@piefed.social ⁨2⁩ ⁨weeks⁩ ago

    There's nothing in the SI system that says ratios have to be between base units. Units that involve mass are defined against the kilogram not the gram.

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    • 7uWqKj@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

      But kilogram is the base unit

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    • Scipitie@lemmy.dbzer0.com ⁨2⁩ ⁨weeks⁩ ago

      You sent me down a freaking rabbit hole, thanks! :)

      From what I found is that there is the simple reason that the weird ones are distance, time and weight - the rest I looked into are based on formal non-normalized definitions (including lumen, which surprised me).

      My guess is that in depends on where the unit comes from: science or day to day use.

      I learned about the Siemens, the Weber and the Gray on the way.

      Thanks again!

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• freijon@lemmings.world ⁨2⁩ ⁨weeks⁩ ago

  This capacitor will cost around one Bitcoin

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  • Tiger_Man_@lemmy.blahaj.zone ⁨4⁩ ⁨days⁩ ago

    Actually no, depending on the voltage it costs from 5$ to 100$ Also here’s 5.5v 1f capacitor Image

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  • sxan@midwest.social ⁨2⁩ ⁨weeks⁩ ago

    We use it to ignite the tokamak.

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• _Cid_@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

  “This magnet has one tesla”

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  • Treczoks@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    That stucks ;-)

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  • kaidezee@lemmy.ml ⁨2⁩ ⁨weeks⁩ ago

    It’s not that much though. You could easily make an electromagnet with magnetic flux density at it’s core of multiple tesla.

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    • marcos@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

      And you can get 1F capacitors in bulk from China for a few dozen dollars each.

      Those things are still dangerous and scary. The 1T magnet way more so than the capacitor.

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  • venoft@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    Most neodymium magnets have like 7 Tesla at their surface.

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• Treczoks@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

  Only criticism is the use of non-metric weight units when everything else is SI-based.

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  • captain_aggravated@sh.itjust.works ⁨2⁩ ⁨weeks⁩ ago

    The joke wouldn’t have worked as well.

    A gram is actually a pretty small unit of weight, and the joke relies on the base units. It’s actually a weird little abberation in the metric system that the “base” unit is considered the kilo gram. so a 1 gram rock would be a little pebble, strangely small.

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• SteveTech@programming.dev ⁨2⁩ ⁨weeks⁩ ago

  Guys you’re not gonna believe this:

  50F Super capacitor

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  • einfach_orangensaft@sh.itjust.works ⁨2⁩ ⁨weeks⁩ ago

    pfff at 2.7V that aint much of a danger, now show me 50F @ 2kV

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  • Kratzkopf@discuss.tchncs.de ⁨2⁩ ⁨weeks⁩ ago

    Yes, I do not believe it. It must be a misprint, right?

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    • SteveTech@programming.dev ⁨2⁩ ⁨weeks⁩ ago

      No it’s real! I can’t verify the exact rating since it OL’s my meter, but with some circuitry it can power my Pi for a few minutes. But I got them from element14, so it’s unlikely to be a fake product.

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• LodeMike@lemmy.today ⁨2⁩ ⁨weeks⁩ ago

  However, 1 farad is really goddamn big.

  Lol, explainXKCD

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• Zoomboingding@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

  Their names are Cueball, Megan, and White Hat?

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  • captain_aggravated@sh.itjust.works ⁨2⁩ ⁨weeks⁩ ago

    It is my understanding that XKCD’s “characters” are somewhere between an actual character and an archetype. It isn’t clear…and kind of doesn’t matter, if Black Hat is the same guy in every comic or if he’s a different devious schemer in each. Randall hasn’t bothered to name any of them so the community has given them unofficial nicknames.

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    • balsoft@lemmy.ml ⁨2⁩ ⁨weeks⁩ ago

      Randall hasn’t bothered to name any of them so the community has given them unofficial nicknames.

      Megan is actually named in multiple comics though, so is Danish (Black Hat’s girlfrenemy). Cueballs also have names occasionally but they’re all drawn the same.

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  • marcos@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    I remember reading about their names in explainxkcd. I think the only one never named in the comics is Cueball.

    For a while, there was a blog, but I don’t think it named any character.

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• Deebster@infosec.pub ⁨2⁩ ⁨weeks⁩ ago

  Ah, Randall is alive! I kept thinking my bot had broken as it’s so rare for him to miss an upload.

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• Hamartiogonic@sopuli.xyz ⁨2⁩ ⁨weeks⁩ ago

  But why pick one pound? The are so many fun units to choose from, only some of which are conveniently sized. How about a stick 1 mile long, or a rock that weights 1 grain?

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  • Simplicity@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    A rock that weighs one stone (14 lbs).

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  • modeler@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    Or a barleycorn that’s one barleycorn long? Or a really large foot that’s a foot long. Or a chain that’s a chain long?

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    • Wolf314159@startrek.website ⁨2⁩ ⁨weeks⁩ ago

      A chain is 66 feet long.

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  • Swedneck@discuss.tchncs.de ⁨2⁩ ⁨weeks⁩ ago

    hogshead is my favourite

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    • Hamartiogonic@sopuli.xyz ⁨2⁩ ⁨weeks⁩ ago

      Imagine what it’s like to calibrate an instrument like that.

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• emeralddawn45@lemmy.dbzer0.com ⁨2⁩ ⁨weeks⁩ ago

  Thats literally exactly what it is. They aren’t derived from the metric system like all units in the system, theyre a specialized edge case where a conversion was specifically written in because america sucks. There are no other conversions in the metric system, units are derived from constants based on a set of specific rules that the pound and yard do not adhere to.

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  • captain_aggravated@sh.itjust.works ⁨2⁩ ⁨weeks⁩ ago

    So, you don’t understand the joke, but you detected an excuse to say America Bad. Your employer must be pleased.

    The joke of this comic is based around most units in both the metric and imperial system being fairly mundane quantities. A one meter long stick is about half the height of a man, a one pound rock is about the size of his fist, a one volt battery has the potential of a dead AA.

    The Ferad is the SI unit of capacitance, equal to 1 coulomb per volt. A one ferad capacitor can hold enough energy to do a number of exotically dangerous things.

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    • emeralddawn45@lemmy.dbzer0.com ⁨2⁩ ⁨weeks⁩ ago

      Lmao what makes you think i didnt understand the joke? We’re talking about units of measurement. And yeah i dont need an excuse to say America Bad. It is bro, have you been paying attention?

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  • Lemminary@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    And I have to say, the chemistry math that resulted from the metric system is elegant. I’ve forgotten most of it by now, but at some point, I was able to envision the machinery behind it all, and it was beautiful.

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• udon@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

  🚲

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  • BrutallyHonestPOS@lemm.ee ⁨2⁩ ⁨weeks⁩ ago

    this guy gets it.

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