Incandescent light lamp flickering is due to what?

[csk]

TL;DR Summary

Incandescent light lamp flickering due to what?
Voltage or Frequency ?

Incandescent light lamp flickering due to ?
Voltage or Frequency ?

 

[BvU]

hello csk,

Is there a complete problem statement in a complete sentence for this exercise ?

Did you read the homework guidelines ?

 

[anorlunda]

This does not sound like homework.

Yes, incandescent lights can flicker. So what? What is your question?

 

[DaveC426913]

It could be due to a damaged filament for all we know.
Define 'flickering'.

 

[zoki85]

Incandescent light lamp flickering due to ?
Voltage or Frequency ?

Variation of the network voltage: https://en.wikipedia.org/wiki/Power-line_flicker
Though if the frequency is made low enough (say few Hz) than the flickering can be observed as well .

 

[berkeman]

@csk -- If you raise the light up a little and pull it in front of the fan like in the picture below, it will stop flickering.

https://image.shutterstock.com/image-photo/retro-typewriter-paper-blank-old-260nw-723124006.jpg

 

[alan123hk]

Summary: Incandescent light lamp flickering due to what?
Voltage or Frequency ?
Incandescent light lamp flickering due to ?
Voltage or Frequency ?

For incandescent bulb flicker that occurs in the daily life of the home, if the choice is limited to these two possible causes, the most likely cause is voltage rather than frequency.

The AC frequency is determined by the generator of the power plant and the frequency is very stable,
and also you should not notice any flickering unless the frequency is greatly reduced, therefore, the possibility by frequency is extremely low.

On the other hand, short-time voltage surges in household AC power sources are not uncommon, I believe that even if the duration of the voltage surge is shorter than tens of milliseconds, you may notice the flicker for the incandescent bulb.

 

[DaveC426913]

Seems to me peeps are making a bunch of assumptions.

Perhaps the OP simply has a bulb with a janky filament?

We don't know the OP's idea of "flickering"; we don't even know the OP's knowledge level of light bulbs, let alone electricity.

Perhaps, if the OP returns, s/he will shed some light on the problem.

 

[sophiecentaur]

Seems to me peeps are making a bunch of assumptions.

Yes. I imagine they all live in USA, too. The 50Hz mains in Europe makes mains voltage lamps flicker discernibly - especially in peripheral vision. The filament temperature varies enough over the cycle for it to vary in brightness - as the Volts vary . 60Hz is very much better in this respect. Also, 240V filaments are thinner than 120 V filaments - for the same Wattage - so they heat up and cool down more over the cycle.
Also, thinner filaments can be more prone to mechanical vibration and you can get low frequency flickering when a bulb is 'on the blink'. I'm not too sure what causes that unless it's a poor contact with the supply posts within the bulb. You can sometimes hear a faint jingling at the same time.

 

[berkeman]

The 50Hz mains in Europe makes mains voltage lamps flicker discernibly - especially in peripheral vision.

Using my Mentor superpowers, I can verify that the OP lives in a country with 50Hz AC Mains power distribution.

 

[sophiecentaur]

Using my Mentor superpowers, I can verify that the OP lives in a country with 50Hz AC Mains power distribution.

The flickering of regular 50Hz lamps in UK machine shops is bad enough to give stroboscopic effects that can make rotating machinery appear stationary or very slow. So much so that it is / was standard practice to use low voltage bulbs which, as mentioned earlier, flicker less with less risk of someone not realising a machine was turning in a noisy machine shop. Nowadays it's worse if 'proper' DC LEDs are not used for lighting.
Record deck turntables used to use three bands around the periphery which would appear stationary when rotation was 78,45 and 33.33 RPM. Not too easy to see but still possible with normal room lighting. My Garrard 401 turntable had a neon lamp which, of course, gave very good contrast. (Strip-Lighting discharge tubes are always dreadful - in most respects)

 

[berkeman]

The flickering of regular 50Hz lamps in UK machine shops is bad enough to give stroboscopic effects that can make rotating machinery appear stationary or very slow. So much so that it is / was standard practice to use low voltage bulbs which, as mentioned earlier, flicker less with less risk of someone not realising a machine was turning in a noisy machine shop.

Oh my gosh! That really is dangerous. Yikes.

 

[Svein]

For a really far-fetched explanation: There is a corrosion on the bulb socket making a sort of diode (anybody remember copper-oxide rectifiers?) which means that the 100Hz flickering (yes, in a 50Hz net an incandescent bulb will normally flicker at 100Hz) will be reduced to 50Hz with a 50% duty cycle.

 

[sophiecentaur]

For a really far-fetched explanation: There is a corrosion on the bulb socket making a sort of diode (anybody remember copper-oxide rectifiers?) which means that the 100Hz flickering (yes, in a 50Hz net an incandescent bulb will normally flicker at 100Hz) will be reduced to 50Hz with a 50% duty cycle.

You may be right about a 50Hz flicker happening in some rare circumstances but perceptibility of flicker has a very soft roll-off with frequency so 100Hz may be noticeable in some circs. Old TVs used 25Hz (or 30Hz) frame rate but they used an interlace system which produced odd and even line scans alternatively, giving 50Hz 'field rate'. Flicker was unbearable, even with that, for some viewers but motion portrayal was judged to be acceptable. Film projectors used to have a shutter which gave two flashes of each frame so the flicker was twice the frame rate. Cinema films were always pretty bad though.
Moderns TVs tend to use double field rate yet the flicker can still be detected sometimes. They are not often 'watched' with peripheral vision.

 

[zoki85]

Before standardization,during early years of AC electrification, around 1900., various operating frequencies were in use in America (25 Hz, 60 Hz,133 Hz...). They found that incandescent light bulbs with carbon filaments ,under normal circumstances, were perceived by people without difference at these frequencies. Interestingly, light bulbs operated by 25 Hz had shorter lifetimes

 

[sophiecentaur]

Interestingly, light bulbs operated by 25 Hz had shorter lifetimes

I imagine they would have shaken themselves to bits with the constant volume changes due to the big temperature range.

 

[zoki85]

I imagine they would have shaken themselves to bits with the constant volume changes due to the big temperature range.

There are various failure modes of incadescent light bulbs, and bigger temperature range at lower frequency is undoubtly very important one (especially for delicate carbon filaments light bulbs). Reportedly such bulbs tended to emit buzzing sounds for quite a long time before they would burn out... Generally higher the voltage and smaller the wattage of an incadescent lamp the flicker will be more pronounced at fixed frequency. Objective measure of the flickering effect is called the flicker index. Two incadescent light bulbs made of same materials, one 100 W, 120 V at 25 Hz, second 25 W, 120 V at 50 Hz, have aprox equal flicker indices. Personally I don't notice any flicker in front of panelboard having12 closely placed small 2 W, 230 V, 50 Hz incadescent bulbs. But I noticed I get tired rather quickly while reading near desk lamp with 25 W,230V,50 Hz incadescent bulb.