I don't know how much tension the wires had. I assume it varied some.
They were installed in a piano.
I don't think the spark was electrical in nature. I'd rather believe
it was a hot piece of metal since I observed it some distance away
from the wire and traveling away from the side cutter. Its color was
brilliant orange. What seemed so odd was that I could repeatedly cut
the same un-tensioned wire and not generate any spark yet most
tensioned wires did spark.
Any possibility it was a visual afterimage,
not a spark at all? The shiny metal could
leave behind an afterimage as it moves
away. You could test this by covering
the wire with black soot from a candle
flame, to see if still "sparks" under the
I'm quite sure it could not have been an afterimage. The wires were
quite old and rusty appearance. The spark I observed did not travel
parallel to the wire but in some other direction (probably random).
Unfortunately I can't repeat the experiment at this time.
As I recall the wires were easier to cut while under tension. Perhaps
just a wire nick caused the wire to part. Could this localized
stretching and failure caused by the tension have caused enough
heating to create the spark?
email@example.com (Lawrence) wrote ....
It is plausible that (given sufficient tension) local stress
relaxation effects might generate temperatures high enough to initiate
oxidation of small bits of metal. Like the sparks generated during
I've observed glass fibers under high tensile stress completely (like
a million fiber diameters) exploding to very fine powder on failure. I
never thought to measure the associated temperature increase. Darn.
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