Blown light bulb again, always wanted to ask this

[Paulst30]

I know its silly however its a childhood thing that maybe a really good electrician can answer. If a light bulb has blown, at which point does the electricity stop flowing to that light bulb, At the end of the broken fillament? The switch? My old physics teacher said that electricity only flows if it has been drawn to a source. confused.com? I have this strange ideal in my head that makes me think that its flowing around in the fusebox waiting for a connection. However that theory might not be right either. People say that to simulate electricity you must think of water and the way it flows, however thats a bit inaccurate too. hmm have i opened a can of worms? lol

[redcrx]

well we were told in physics that its at the end of the filamant but not flowing as it has nothing to flow to.

[Toleman]

As it cannot be stored more has to be produced at peak times

[Gef]

The electrons which are responsible for the electric current are there all the time - in the wires, filament etc. When the filament breaks they just stop flowing. Simple.

[Teddio]

There is a potential difference of 230V ac across the filament. The filament in a 100Watt bulb will have a resistance of 529 Ohms and a current of 0.43 Amps will flow through it. When the filament breaks, the resistance will rise enormously to billions of Ohms: effectively an open circuit. There will be an initial arc as the filament breaks but the current will drop to zero as the pd is insufficiently high to sustain a current through the gas.

[dougielogan]

Is a battery not used for storing electricity?

[Paulst30]

So the conclusion is that if you have a broken light bulb and at that point when your looking at the wire, NO electricity is flowing through it so its effectively dead until the point where the current has source i.e possibly me if i touch the wire, then it becomes live.


Because electricity travels in nano seconds it appears that there is current in the wire, however its only when electricity has a source and a return.

[jake-the-peg]

G4GS I'm very interested in your answer to Gef that electrons don't move but the charge does

What do you suppose carries the charge? Please elaborate

[mibn2cweus]

When an incandescent light bulb filament burns out a gap is created that acts essentially as an open switch. The force (voltage) is present across the gap but the path that enables current to flow (a continuous filament) is missing. In a clear glass bulb that has burned out you will usually see both ends of the broken filament drooping from their posts. A force of several thousand volts is generally required for electricity to jump a gap of one millimeter, however due to exceptions too numerous to list here this should not be tested without a thorough understanding of proper safety procedures.