I'll try, but I'm very possibly wrong, please correct me.

1) When the circuit is closed, think of the two contacts approaching
each other slowly. At some point they will be close enough so that the
voltage different is higher than the breakdown voltage of whatever is in
between them, like air for example. This then causes the air to ionize
which forms a conductor channel, and that's a spark - the brightness
depends on, among other things, how much current is drawn through this
channel, which is why heavier loads spark more.

2) the ionization of the air forms ozone, which has a certain smell. It
may also be that the contacts are slightly singed now, which would also
smell funny.

3) The best way to test if an outlet is live is using some sort of volt
meter (that can handle the line voltage!). Alternatively, you could put
some sort of load there like a resistor that will heat up but not burn
out, or a lightbulb. Touching them together may do Bad Things (tm): You
could just cause a circuit breaker to flip, or worse yet, you may
overload an already frail circuit that has poor wiring, thus causing
overheating at an inferior wire joint and subsequently burning the house
down.

- Marcel

G=F6khan SEVER wrote:
> Goodmorning PIClist members,
> =

> I've three basic questions related to electricty. They are coming from my
> deeper curiosity. Actually i did some experiments but still wondering the
> real explanations of these concepts.
> =

> 1-) Why do sparks exist when we make touch the (+) line to the (-) line of
> dc voltage or (phase and neutral line of AC)?
> =

> 2-) Where is the source of scent after touching the two lines to each oth=
er?
> =

> 3-) (Although this one is a bit foolish question) Is it wiser to test the
> existance of the electricity on the AC line by letting touched phase and
> neutral lines?
> =

> =

> Even the basic electricty book recommendations are very welcome.
> =

> Have a nice day,
> G=F6khan SEVER.

-- =

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