h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Nice work, that man

Thank you, that man.

I particularly enjoyed writing this, as it happens.

B

So has this become a classroom hand-out then?

"Right - I can't be bothered to teach you today, so learn this"

Traveller in Time checking the date
"Great entry, covers a lot. . .

Only why did I drop this t<./>info</.>il in 1800? I know I would make some time confusion.

(Aluminium is anachronism in list )"

Is the speed of electricity different in different metals, then?

RF and I were discussing this the other day a propos doorbells. Namely, he can't work out what his sounds like. I said all he needed to do was go downstairs, push the doorbell, and then run upstairs again faster than the speed of sound to hear it .

But when we thought about it, we agreed it would have to be faster than the speed of electricity.

But just how fast is that, eh?

Traveller in Time using an extension cable to hear the frontdoor bell at the backdoor
"Propagation speed of electricity is way higher then the speed of sound. Different for each metal or alloy, frequency, temperature and even for changes in conductor material.

"

Nice entry! Easy to understand and fun to read.

Hey Lucky Star. If you mate's door bell produces a sound with metal chimes electricity is not the direct cause of the sound. That is produced by little hammers hitting metal bars or a bell. The electricity works electro-magnets that move the hammers. If it's not this type of door bell then it will produce a sound via a circuit through a speaker (electro-magnet again, this time vibrating a paper cone) or in the case of Transylvanian castles a large rope operating a bell on a pivot.

turvy

Hmmmm...

To be more specific: how long is it between the time Visitor X presses the doorbell, and RF, 2 floors up in his flat, hears the resulting ring.

Surely there's electricity involved between the button and the whatever-it-is device making the noise!

Traveller in Time calculationthe propagation speed of the rope
"Is it a steel wire, natural fibre or rubberband rope?"

'Star, to cut through the banter and answer your question - to all real purposes, no. Electrons move at the speed of light, and any interference effect from the metal atoms only serves to stop electrons moving or to create more friction. The change of speed is negligible.

B

Thank you dear.

As I thought about it, I remembered that the movement of the electrons in a wire is all at once, isn't it? It's not one electron at the bottom of the stairs having to make it all the way up 2 flights...it's the electrons already at the end of the wire where the elctro-magnets (or whatever) are.