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Physics tommorrow?! watch

1. Help!
Does anyone know wat an alternating voltage is?
2. I would guess it's what causes an alternating current... the electrons don't go back and forth by themselves...
3. urm lol now i feeel well dumb... wats an alternating current?
4. (Original post by Dust)
urm lol now i feeel well dumb... wats an alternating current?
Current reverses direction 50 times a second, so the electrons move one way, then 0.2 s later they move the other way, back and forth. So a lightbulb left on for a week will have exactly the same electrons as before. The power is still transferred just as fast though, because those electrons are still moving to an area of lower potential and are still heating up the filament when they do.

In continental Europe they have DC, so there is a slight problem with the Eurostar. They have to have a converter so that it can run off the UK's power supply (AC) as well.

Check the diagram I drew (a bit scrappy), the diodes can be used to convert AC to DC.
Attached Images

5. as in ac and dc? where the little electrons go back and forth instead of just forth? ahh gawd, physics 2mo u say....
6. (Original post by mik1a)
In continental Europe they have DC, so there is a slight problem with the Eurostar. They have to have a converter so that it can run off the UK's power supply (AC) as well.
Are you sure?
How would their high voltage grid system work? They wouldn't be able to use transformers to decrease the voltage or anything. and didn't we have to drop our mains voltage to come in line with theirs a few years ago, from 240-220?
7. (Original post by scarlet ibis)
Are you sure?
How would their high voltage grid system work? They wouldn't be able to use transformers to decrease the voltage or anything. and didn't we have to drop our mains voltage to come in line with theirs a few years ago, from 240-220?
I'm not sure, just something I saw on a GCSE physics video a while ago. And yeah I think there is something about mains voltage being 230 V... I'm not sure, I always thought it was 240 V but for A while I've seen it written as 230 V in exam papers and books...
8. (Original post by mik1a)
I'm not sure, just something I saw on a GCSE physics video a while ago. And yeah I think there is something about mains voltage being 230 V... I'm not sure, I always thought it was 240 V but for A while I've seen it written as 230 V in exam papers and books...
UK mains is definately 220V (i just asked my dad, who's an electronics engineer!)
they use all sorts of random values in exams.
9. thanx ppl!!!

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