a flash when heated

[boy_genius]

i was messin round with one of those car jumper battery packs and i attached one clip to a lenght of galvanised metal an tip it to the other connection the thing sparked really bad like with a welder and heated up as it heated up the sparkin end began to spark like magnesium when it first lights then a great big green flash took over an a cloud of greenish smoke a white powerder was left on the remainin wire whta the hell happened?

[brachiopod]

Then u issunt dat much of a boy_genius an fings an dat, innit? tw@t

[jake-the-peg]

This wouldn't happen to be another cunningly disguised homework question would it?

There just seems to be a suspicious amount of relevant detal - galvenised metal - green flash - green smoke - white powder?

Well lets see you've shorted out a car battery which will cause a large electrical current to flow - it sparks because as you connect it there is a point where the gap is so small that the electricity jumps the gap. creating a lot of heat

As for the colours and the powder the key point is that galvenised metal is coated in zinc.

  Have a look here http://www.scorecard.org/chemical-profiles/html/zinc.html especially the bit about burning in air and see if that helps

especially the bit

[Thunderchild]

ps be very careful if this is not a homework question and you r messing around, a car battery can source a lot of current all in one go and all that goes into heat as jake-the-peg said. you be dealing with 0.5-1 KW of power so TTRRYY not to cause a fire or burn your self the good news is 12 Volts will do you no harm.

pps a welding machine is pecisely what you did: a short circuit but a controlled one the high resistence at the joining point causes all the heat that does the welding the bad news is don't improvise with the car battery as it is you may have done some damage to it (assuming you realy were fooling around and not quoting a school book example)

any how god luck either way

[Hamish]

I have a funny feeling that a lot of people see to have been doing this sort of thing recently. If you stopped meesing arround and listend to the lesson you might know the answer!

[Mortartube]

The green flash was probably caused by the zinc galvanised coating. There are a couple of formulae for firework stars using zinc. They make a sort of electric green colour like a short circuit spark.

Don't breathe in the smoke or you can get "Zinc flu", a condition some welders experience after welding galvanised plate. It feels just like influenza, hence the name.

And don't mess about with car batteries etc. They can be surprisingly powerful and cause serious burns.