The Periodic Table - 2015-09-25

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Martin - マーチン

9:55 AM

@inɒzɘmɒЯ.A.M Happy now? (╯°□°）╯︵ ┻━┻

@inɒ Do this, too!

10:22 AM

0

Q: Citation style recommendation/standardisation

As our Resources for learning Chemistry thread is now established and is growing with input from many people around the globe, we have to deal with everyone's personal favored citation style. Orthocresol changed my citation style for the books to sth he likes but left all other answers untouched...

:O

soundslikefiziks

10:44 AM

Electromagnetic waves anyone ?

:P

2 hours later…

12:40 PM

@soundslikefiziks, no waves here. :D

Only humans and cats.

And molecules.

Oh, wait! @pH13, is an orbital! He is the wave function! :D

hehe

~~~~~

He2? :O

He_n

1 hour later…

soundslikefiziks

2:03 PM

@Wildcat Haha

2 hours later…

soundslikefiziks

3:36 PM

@Wildcat Do you feed stray cats?

1 hour later…

5:01 PM

@inɒzɘmɒЯ.A.M When is the first retagging event?

5:28 PM

@soundslikefiziks, =O.O=

Should I?

soundslikefiziks

nope

i mean @Wildcat Nope.

Humans should!

:D

soundslikefiziks

Haha oh....

Alas, a talking cat!

a printing cat :D

soundslikefiziks

typing typing

5:32 PM

yeah, whatever

but listen

even if a talking one

soundslikefiziks

Aha! i wont fall for "Listen" !

WHAT'S SO STRANGE ABOUT IT?!

I mean

soundslikefiziks

nothing, i'll just want to know how you got here

you, humans, believe in so many unbelievable things

like god, democracy, ...

soundslikefiziks

not all talking beings can work a computer let alone sign up for a website

we don't

5:34 PM

but the come a talking cat and everyone's reaction is "What?! A talkin cat?! No way!"

@soundslikefiziks, well, many of you do. :D

actually, I once talked to a cat on the phone

soundslikefiziks

Well so it can't be "you humans" ! coz some of us don't

for example, all cat's share the love for meat

@Loong, good of you. But don't say it to a psychiatrist! :D

soundslikefiziks

until you show me a vegetarian one

haha

@soundslikefiziks, media.catmoji.com/post/cs8s/vegetarian-cat.jpg

XD

soundslikefiziks

5:36 PM

I guess he'll vomit that soon enough

@Wildcat quantum chemistry also means you're good at physics ?

@soundslikefiziks, not as good as I would like to be though. :|

soundslikefiziks

which will of course lead to another question muhahaha.

:O

soundslikefiziks

well, you wouldn't by any chance know how to explain the shape of an electromagnetic wave would you ?

Кот испугался огурца

soundslikefiziks

5:40 PM

Hahaha

i don't know what's funnier , the cat or calling a cucumber agurets

@soundslikefiziks, what's your problem with their shape?

Do you want to know why are they sinusoidal?

soundslikefiziks

well, first , if they can be represented by one sine wave , i want to know which parts of this wave represent the magnetic field and which represents the electric field

otherwise they should be represented as two separate sine waves

@Wildcat , sorry i forgot to @, now you know i replied :)

:D

OK, so, when I said EMW is sinusoidal I meant its usual pictorial representation

soundslikefiziks

so,

two sine waves (of electric and magnetic fields) in perpendicular plane

$user image$

here is the mathematical description

soundslikefiziks

5:49 PM

Ok so why do they advance forward ?

or 'outwards'

i know that one creates another

by why not one collapses another into oneself destroying the field

i mean, when you move current to one direction you create half a wave, right ? or only a full cycle can start the propagation ?

(I am talking about current through an Antenna

I don't quite understand what you mean.

I never studied EM deeply since I hate it. :D

But...

What do you mean by collapse? Electric wave collapsing with magnetic one?

soundslikefiziks

Well, the problem is, it's a very basic question apparently which i still cannot get.

i mean , a change in electric field creates a change in magnetic field

so when you gradually increase the current through a circuit on one direction it is creating a magnetic field around it , right ?

a changing magnetic field, yes.

so far, so good

soundslikefiziks

my first question would be , will that magnetic field also create an electric field outwards? even if technically we only finished half a cycle ?

5:55 PM

what do you mean by "finished half a cycle"

?

soundslikefiziks

i mean a cull cycle would be increasing the current on one direction lets say from 0.1 to 1A

And then we would reverse the direction

ok

soundslikefiziks

and take it from 1A to zero and from zero to -1A

the electric field would be inwards, as the wire would be negatively charged. the field would still point inwards, even if the direction was reversed.

soundslikefiziks

you mean outwards?

5:58 PM

inwards. E is for positive charges. the wire would be negatively charged with a moving current.

soundslikefiziks

So why wouldn't it just destroy the magnetic field ?

like what happens in a coil

when current is reversed

because electric fields don't induce current OR magnetic field, they're independent

current and magnetic field are dependent on only eachother.

soundslikefiziks

So what will then happen with the magnetic field created by the change ?

by the change in current*

the current will 'want' to continue to flow, even when a drop in potential occurs.

soundslikefiziks

And , ? it would take the form of what?

6:02 PM

the magnetic field would then create it's own potential, and dissapate itself in the process.

that's the principle of electric inductors.

soundslikefiziks

:O nice. nobody told me that

yeah, I can see why that would be confusing.

soundslikefiziks

but in an inducer when current stops the magnetic field collapses and current then flows inside the circuit in the other direction, not outwards as a wave

What you are saying is that it also created a potential that propagates outwards and creates an EM wave?

sort of.

so, when you apply a current to an inducer and then stop suddenly, the magnetic field creates it's own differential (volt [Joules/culomb])

and that, in turn creates a current, a flow of electrons.

soundslikefiziks

Ok that would explain it for an inducer, but not all antennas look like inducers, i mean, most of them are just a straight line

like a radio antenna

6:07 PM

anything that can hold a current is an inducer. albeit much less potent.

soundslikefiziks

but it seems there is a great different in inductance if you add several loops

because of the formation of the magnetic field

yes, and the field is contained within the loops, thus reducing the size of the field.

so, that makes coil-based inductors very potent

i'm not so well versed in radios.

soundslikefiziks

but is there a need for inductance at all in order to create an EM wave ? i mean , according to the law , a change in current is suffice

a change in current, is a change in magnetic field, and that magnetic field (EM wave) causes induction

soundslikefiziks

and that what 'drives' the wave ?

6:12 PM

I have to go for now, I hope that I didn't do the '2 steps back' part

the wave IS the current.

soundslikefiziks

All cool , Thanks :)

o7

soundslikefiziks

o7 :)

2 hours later…

inɒzɘmɒЯ.A.M

8:39 PM

@bon Next Friday. This German mod was so laid back for a quick start.

@Martin-マーチン One by one.

@Martin-マーチン Have I told you that you're a lovely guy?

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The Periodic Table

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