Why does a light bulb flash right before it goes out?
954358
Its the same principle as a welding arc. when the bulb goes out the philament breaks into two pieces. When they split apart, before they get too far apart, the electricity jumps the gap causing a bright flash. After that the current cant make the leap so the bulb is dead.
1046964
It's actually normal.  I know that if some people stare into flashing lights (kinda like a strobe light)  it can make them go into seizures. it has something to do with the brain and the light, I am not real sure what could cause it maybe it is the motion of the light and the brain not being able to process it fast enough.
757280
Both. \n\nCheap Christmas lights are connected in series circuit to save money in materials.\n\nAverage Christmas lights are connected in groups in a series/parallel circuit, so when one bulb goes out, only the gorup that, that light bulb was in will go out.\n\nExpensive Christmas lights are connect in parallel circuit so that when one goes out, all of the others remain on.
928685
An electric INCANDSCENT bulb uses a tungstene filament (twisted wire) that is heated by the current passing through to several hundred degrees.  It is this heat that heats the glass.  It is also the proof of inefficiency of the bulb, because it is transforming 80% of the energy it receives into heat, giving only 20% for light!\nIn the FLUORESCENT tubes, the light is produced by the ionisation of the internal gas (neon or argon).  This ionisation is initiated by heating two small filaments at teach end of the tube, that heat up a small drop of mercury.  Once the mercury is vaporised inside the tube, the "starter" opens, creating a high voltage puls across the whole tube, ionising the gas that then becomes conductor: a small current passes through the gas, and the filaments are disconnected.  Since the ionised and conductive gas has nearly no resistance, the current is limited by the "ballast" (an inductor inserted in series).\nSince the CURRENT is limited, there is no "Joule Effect" (heating) and the tube stays pretty cool.\nTheir efficiency is about 100 times more than a bulb... (in terms of power/light ratio).
603423
Electric light is produced by running an electric current through a resistor that then glows white-hot.  Edison searched through thousands of different materials to find one that glows just right.\n\nToday most regular light bulbs use a tungsten filament (a little wire made of the material 'tungsten') which gives off a lot of light but it is relatively breakable.\n\nWhen a bulb 'burns out' it means that this little filament has burned up or broken.  It is more likely to break when it is turned on.  Technically I suppose you could get more life out of a bulb by leaving it on all the time but that would be a waste of energy and you don't want light all the time.\n\nThese days there are other materials and other ways to make light bulbs that last a lot longer but they are not in common usage yet.
57097
The bulb could be getting ready to burn out.\n\nOr the street light could be "cycling". Sometimes, a streetlight is installed in a bad location. When it gets dark at night, the light comes on, but the light from the bulb is reflected back to the photocell. The photocell senses the light and thinks it's daytime again, so it shuts off the light. When the light shuts off, the photocell senses that it's dark again and turns the light back on. Then it keeps cycling on and off. Each cycle lasts about a minute or two depending on the manufacturer of the photocell. This usually happens with the streelight is near a shiny marble wall or a building window.
1113253
Dude, \n\n   You have to reword your question. It really doesn't make much sense. Here's my interpretation of the question:\n\n"An AC voltage (230v/50Hz) is applied to a light bulb. If the frequency is reduced to 10Hz will the light flicker?"\n\nAnswer is yes. We do not see the 50Hz flicker, because of persistence of vision.
168586
The light bulb uses radiation which is not as effective as convection in this case.
818868
I suspect this refers to how flourescent light bulbs generate a quasi-continuous spectrum as opposed to the discrete emission lines like other self respecting plasma discharge tubes.  \n\nHere is a website that has several pages on Flourescent Lamps:\n\nhttp://home.howstuffworks.com/fluorescent-lamp.htm\n\nThe first two or three are the ones useful to you.  Also there are several links on the last page under More Great Links that will help you in your researches.  Happy hunting!\n\nBTW: This reeks of an intro science class lab write-up question.  TAs at help desks or profs during office hours can help a great deal more effectively than something like yahoo answers, if you want to truly understand.
136786
They want to be really sure it's out before the go to all the trouble of figuring out how to change it.  Some kinds of fluorescent lights will sometimes come back for a few minutes if you to that, though.\n\n_____\nThe previous answer explains why the would turn it off and then on, but the question asks about on and then off :-P
515931
If you stick two electrodes with a light bulb into salty water, the light will shine brightly, showing that it really is a good conductor of electricity. The more ions you add, the more brightly the light will shine.\n\nSo in other words, it sure is a good conductor and it is one because of the NaCl-  (Sodium chloride) in it.
697078
the is rotated in the magnet with the help of the wheels which are turned by the driver. this induces electricity to flow through the wire. this electricity is used to light the bulb.\nlook up electro magnetic induction.
89866
air is not necessary for a lightbulb to burn. but due to the zero atmosphere it would most likely explode unless encased in a pressurized vessel.
82937
The electric company generates (makes) electricty, which they send through wires. These wires go to every house. In some places, you can seem them on the street, but in most places they are underground.\n\nWhen you flip a switch, your are connecting the lightbulb to one of these wires. So electricity flows from the wire to the lightbulb. When you close the switch, you disconnect the 2 wires.\n\nThat is what happens. How electricty is made, and how lightbulbs and switches works is a bit more complicated, but for that I suggest Wikipedia:\n\nhttp://en.wikipedia.org/wiki/Electricity\n\nThe basic idea behind generating electricity though, is that you are freeing electrons from atoms, which then go to other atom/s that absorb them.
29771
This is cause by a blackhole that is inhabiting your shadow. The gravitational force of the blackhole sucks the light from street lamps and causes a temporary popped circuit. Once you pass the light should come on after the breaker cools.\n\nWhat is unfortunate is that SLIders have a negative effect on traffic lights and sometimes actaully make the red lights last longer or the green lights shorter. Oddly SLIders have no effect on yellow lights whatsoever.
1156389
Where did the light go when the light bulb over your head burned out?
174509
Ours don't do it every night, but they do it occationally (like once a week or so). I was told it was because the bulbs tend to accumulate moisture inside them and if you don't heat up the bulbs to reduce the moisture level periodically, when you do turn them on they will all tend to blow out really quickly. So, I guess that means using them makes them last longer.