Electricity flow

[pgarner]

just got a new inline fuse for the amp as old has shattered in the cupboard. on reading the instructions it says to install the fuse within 15" (45cm) of the battery why is this??

if i remember correctly, in scottish schools we are taught proper physics where electricity is the flow on electrons which are negitivly charge which flow towards the protons, positive charge.

we were told at the time (around 2001) that english schools were taught conventional physics where the electricity flows from the pos to neg

can anybody please explain i have got a higher physics (a level) but cant work this 1 out.

added the poll as wanna see which way you were taught

[aswearing]

gcse told me po to neg. im you bioscience mad, hated physics (but was best subject )

[pgarner]

yeah a thought gcse and a level taught it pos to neg. id like to know why as apart from making things easier to understand its a lie

[aswearing]

test it with a battery and led

[pgarner]

yes but leds tell you to connect the cathode to the negitive

thats what im getting at it makes it easier to learn when you are told that it flows pos to neg

but the electrons are negitily charged and are the ones which switch places when electricity is in use

electons from the battery neg swap with ones in wire led other wire befor getting back to the pos in the battery

[HDi fun]

Current flowing positive to negative is the conventional thinking.

This is as a result of electrons (which are negatively charged) moving from negative to positive.

You could also think of it as 'holes' moving from positive to negative. Holes being holes that are about to be occupied by an electron.

For ALL electrical purposes current flow is from positive to negative with no exceptions.

[fingers]

Are we talking AC or DC?

[HDi fun]

Originally Posted by fingers

Are we talking AC or DC?

Both!

Current flows from the positive side to the negative side. This can be used for all situations. With AC, the current flow changes direction periodically and regularly. With a 0v anchored 'negative' the 'positive' changes in voltage and current amplitude occur 50 times per second in the UK in a domestic or industrial single phase supply. Current flow (volts don't flow!) often lags behind voltage in AC systems. Inductive or capcaitive systems exhibit a behaviour known as reactance. It's inductive reactance that fires the coil packs in your spark igintion car's spark plugs.

So, if the positive [live] is a minus 50 volts then current flows from the negative to the positive. But, of course, the roles are reversed and current flows again from positive to negative. Of course, the electrons are still moving to fill 'positive holes'.

I think the problem is that voltage is only relative to another reference point. As such, I prefer the term, instananeous potential difference.

Electrons will always move away from a point of lower voltage potential to a point of higher voltage potential. That's because they are carrying a negative charge and try to correct the imbalance in a circuit.

So, to summarise, AC is only DC changing direction periodically.

As for three phase (and, yes, your car's alternator is almost certainly of three-phase operation.

That's for another post.

Regards,

Paul.

[pgarner]

cheers