As a teenager ( I a'm now 57) I would often
hear that if you were to drop a flashbulb
(one of the smaller, tube shaped ones) down
into the gas tank of a car,that it would
set in the tank,slowly desolve, then when the
plastic was gone,for somereason, the gas would
make the flashbulb"flash" hence KABOOM!!!
Ever heard of this one? Can it be possible?

Thanks, " Slimgrady"

I dont remember any flashbulbs being self-powered - they were just a sealed glass tube with a lot of thin wire on the inside. All that happened was that power from the external battery was applied, and the wire was heated very rapidly through incandescence to vaporising.

I dont think it could happen, the wire in the bulbs is heated by resistence until it becomes so hot that it glows therefore emitting light thats why they blow so often they can only take so much heating and cooling. If the filiment went as far as vapourising the bulb would not last long enough to be of much use imo.

quote:

Originally posted by Jake2010:
I dont think it could happen, the wire in the bulbs is heated by resistence until it becomes so hot that it glows therefore emitting light thats why they blow so often they can only take so much heating and cooling. If the filiment went as far as vapourising the bulb would not last long enough to be of much use imo.

That's because flash bulbs can only be used once. As the name describes they flash!

quote:

the wire in the bulbs is heated by resistence

Lots of thin wire, not much resistance in the filament, but enough current passed through it. Its the power realised by passing current through the resistance driven by the voltage from the battery that causes heating, not the resistance which is merely a passive quality of the wire.

quote:

If the filiment went as far as vapourising the bulb would not last long enough to be of much use imo.

That is exactly how flash bulbs worked.
They were very much a "use once only" device, the filament was destroyed, and usually the glass or plastic shell was deformed. They should not to be confused with flash tubes, which contained xenon gas and were presented with a very high voltage at the terminals, causing ionization of the gas, and the characteristic discharge of energy in the form of light, and could be re-used as long as the charger circuit could recharge the capacitor.