this post was submitted on 25 Jun 2025
453 points (97.7% liked)

xkcd

11723 readers
139 users here now

A community for a webcomic of romance, sarcasm, math, and language.

founded 2 years ago
MODERATORS
453
xkcd #3106: Farads (imgs.xkcd.com)
submitted 2 days ago* (last edited 2 days ago) by xkcdbot@lemmy.world to c/xkcd@lemmy.world
 

xkcd #3106: Farads

Title text:

'This HAZMAT container contains radioactive material with activity of one becquerel.' 'So, like, a single banana slice?'

Transcript:

[Cueball holds a stick while talking with Megan and White Hat.]
Cueball: This stick is one meter long.
Megan: Cool.
White Hat: That's a nice stick.

[Cueball holds a smallish rock.]
Cueball: This rock weighs one pound.
Megan: I'd believe it.
White Hat: Looks like a normal rock.

[Cueball holds a small battery.]
Cueball: This battery is one volt.
Megan: Seems fine.
White Hat: Might need a recharge.

[Cueball holds a capacitor while Megan and White Hat panic.]
Cueball: This capacitor is one farad.
Megan: Aaaaa! Be careful!!
White Hat: Put it down!!

Source: https://xkcd.com/3106/

explainxkcd for #3106

you are viewing a single comment's thread
view the rest of the comments
[–] SomeoneSomewhere@lemmy.nz 2 points 2 days ago (1 children)

Still tens to maybe low hundreds of microfarads.

[–] ByteJunk@lemmy.world 3 points 2 days ago (1 children)

Oh. I thought it would be more impressive, but that's still orders of magnitude away. Thanks!

[–] bizarroland@fedia.io 2 points 2 days ago (1 children)

And when they are used for air-conditioning units, they are typically boost capacitors, which means they store up a nice amount of juice for when the compressor powers on and needs a sudden rush of energy, but that's only a very small amount, like you couldn't crank a car with the amount of energy in these capacitors.

[–] SomeoneSomewhere@lemmy.nz 1 points 1 day ago

No. They provide phase shift to give the single-phase induction motors a rotating rather than oscillating magnetic field. They charge and discharge 100/120 times per second depending on grid frequency.

They do not cover inrush current, and would need to be orders of magnitude bigger and a different topology to do so.