## Coaxial Cable

so Bell solution was to take two pairs

and twist them around each other which

is very smart okay but like I said it's

got problems especially as you go over

longer distances this is what Rick you

are saying okay that our little bit of

interference that can come in over a

long distance it's really going to add

up okay so people decide this stuff this

is called coaxial cable coaxial cable is

where once a lot of time

you should have dial-up internet or you

used to have cable internet mail iPod on

dial-up internet it still comes through

cables right well the cable of cable

internet is coaxial cable so let me try

to explain this okay here's a diagram

once though it's not a diagram it's a

photo okay you can see it's quite on a

small scale okay and you've got these

four different elements okay so let me

go through each one what you've got in

the middle is just a single copper wire

a single copper wire okay so if you like

I'm going to cut it across ways and I'm

going to look at it side on so this is a

okay what are we looking at now just

before I am I give you any more details

apart from the fact that you've got this

single copper wire in here I should say

it's single that's important why is this

called coaxial cable what do you think

is the word that's underneath sorry

start again

what does KO mean when you put ko on the

front of a word what does that mean like

coordinates or coordination or together

right so things that are doing the same

thing right when you've got current in

front of axial what do you think is the

axial is a is an adjective

what do you think is that now on

underneath axial axis right so the idea

here is all of these different layers

there's this four okay they all share

the same axis of symmetry okay as

opposed to this twisted pair these have

opposite um axes right but coaxial cable

everything's on the one axis so that's

why it's called coaxial okay so what are

the things that are sharing in acts as

well number one you know this couple lap

number two you've got this insulating

here it's usually plastic okay then what

you got is actually and if you can you

know see it make it out on the photo

what's this part here this is metal why

don't they put metal there it's not to

trade those signals what's that metal

for yeah

good again we're trying to cancel out

things coming from the outside okay so

they call that they call that part a

metal sheath okay so again it's trying

to cancer the electromagnetic

interference in the same way that a

second cable would but it does a much

better job okay lastly you just have a

wrap up for this so you can you know

hold it with your hand and you're not

going to be caught in the middle okay so

this stuff is a lot more expensive okay

because for every coaxial cable you've

just got one signal whereas for twisted

pair you've got double right and also

all the extra layers and that kind of

thing particularly this metal sheath

they're quite expensive to produce

okay so coaxial cable is more costly but

it can go much further and you can send

more data through it more reliably

that's why cable internet is so much

faster than dial-up okay because you can

send through things here and know that

over a long distance there's going to be

less interference okay