100 Watt Light Bulb Amps
Why doesn't a light bulb draw 100 amps?
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- Why doesn't a lite seedling draw 100 amps?
My father said he does not sympathize why a simple light bulb in an Ac circuit does not depict far more amps than a unproblematic light bulb draws. He thinks that a typical light bulb only draws something approximately like a tenth of an amp. His intuition would make him guess that a light seedling would draw far more than amps than the light bulb needs, but a simple light bulb only draws something like a 10th of an amp. Why doesn't a light bulb draw 100 amps?
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P(ower) = I(current)**ii x R(esistance),
so 100 Watt = I**two ten 100 ohm
and thus I**2 = 1 and thus
I = 1 (amp)
It would if it were a 10,000,000,000 watt seedling with a ane,000,000 ohm filament (this is equivalent to stringing 10,000 100watt bulbs together and supplying 100,000,000 volts beyond the string).Summary:: Why doesn't a light bulb depict 100 amps?
Дагесян Саркис Арменакович, Wikipedia
I just measured the (cold) resistance of a 40W 120V bulb as 22 ohms.For a 60-watt 120-volt lamp, the uncoiled length of the tungsten filament is usually 580 millimetres (22.8 in),[61] and the filament diameter is 0.046 millimetres (0.0018 in).
The common cold resistance of tungsten-filament lamps is about i/15 the resistance when operating. For example, a 100-watt, 120-volt lamp has a resistance of 144 ohms when lit, but the cold resistance is much lower (about nine.5 ohms).
Others gave numerical answers about what a light bulb actually does, simply I'grand just plain dislocated by your question. Why does a low-cal bulb depict what a light seedling draws? Why is blueish blue? Why is 1 ane? Why does a duck quack like a duck? What is the meaning of is (is)? As asked, the question makes no sense. There must be a thought process behind it that y'all aren't (he isn't) telling us.My father said he does non sympathise why a simple light bulb in an Air-conditioning circuit does not draw far more amps than a simple light bulb draws. He thinks that a typical low-cal bulb only draws something approximately like a tenth of an amp. His intuition would brand him guess that a light bulb would draw far more amps than the lite seedling needs, just a simple light bulb merely draws something like a 10th of an amp. Why doesn't a calorie-free bulb depict 100 amps?
In order to adequately answer the question, I call up y'all need to tell u.s. why he thinks a light bulb should draw more than a light seedling draws. Why should 1 = 5?
Yup, this.Others gave numerical answers almost what a calorie-free bulb actually does, but I'm only patently dislocated by your question. Why does a calorie-free bulb depict what a light bulb draws? Why is blue blue? Why is 1 one? Why does a duck dishonest like a duck? What is the meaning of is (is)? As asked, the question makes no sense. In that location must exist a thought process behind it that you lot aren't (he isn't) telling united states of america.In order to adequately answer the question, I think you need to tell us why he thinks a light bulb should draw more than a light seedling draws. Why should ane = 5?
I spent several years working with a low-cal bulb (OK, laser actually) that drew 65A at nearly 600Vdc. It all depends on the blueprint of such things.
The filament will not draw 100 amps if the filament bulb designer does not want it to draw 100 amps.Why doesn't a light bulb draw 100 amps?
The operating voltage is very of import in deciding the resistance of the filament needed to avoid it fusing immediately.
Say 230 volts, 100 watts, the operating current will exist 100 West / 230 5 = 0.435 amp.
The resistance of the hot operating filament will be 230 5 / 0.435 A = 530 ohms.
Simply filament resistance is proportional to absolute temperature, (which helps regulate electric current).
The common cold filament will be at about 293 Yard, while the hot operating filament will be well-nigh 2930 Thou.
That is a factor of 10 modify in absolute temperature, and as well in filament resistance.
The cold filament volition therefore have about one tenth of the hot filament resistance.
When turned off, the 530 ohm hot filament will come down to near 53 ohms.
At the instant the calorie-free is turned on, the filament current will be 240 V / 53 ohm = 4.5 amps.
Then every bit the filament chop-chop heats, resistance increases by a gene of 10, and the electric current falls to the designed 0.435 amps, for 100 watts.
At present what nearly a 12 volt, 120 watt filament globe ?
Operating current will be 120 West / 12 V = 10 amps.
Common cold start electric current will be 10 times hot = 100 amps.
Which shows that some filaments volition draw 100 amps sometimes.
A 12V globe running on 100 amps continuously would radiate one.2 kW.
100 amps times 115 volts is 11500 watts, and so for 100 watt bulbs wired in parallel, 115 of them would draw 100 amps.Information technology would if it were a x,000,000,000 watt bulb with a ane,000,000 ohm filament (this is equivalent to stringing 10,000 100watt bulbs together and supplying 100,000,000 volts across the string).
In the US, house outlets supply current at about 115 volts. The circuits are usually limited to 15-30 amps of current by fuses or circuit breakers that will accident (fuse) or trip (billow) if more their rated amperage is demanded by whatever is plugged into the outlet. Given that watts = volts times amps, 100 watts at 115v draws about 0.87 amps.Summary:: Why doesn't a calorie-free bulb draw 100 amps?
True. I decided to utilize serial as an instance because I knew the numbers would be outrageous.100 amps times 115 volts is 11500 watts, so for 100 watt bulbs wired in parallel, 115 of them would draw 100 amps.
This question is really not clear, and for an unclear question any answer would just make thinks worse.His intuition would brand him guess that a light bulb would draw far more amps than the light bulb needs, but a elementary calorie-free bulb simply draws something like a tenth of an amp.
I remember he should only challenge his own intuition and work some more than on that question first. A good question is always half of an answer
The question asked is "Why?" and the respond is that nobody wants to purchase a seedling that produces 1000x equally much light every bit needed and costs a hundred dollars a day to operate. So information technology should be no surprise that the light bulbs in your business firm don't do that.
What people seem to exist answering is "How?" (which might be what the OP wants to know). @.Scott answered it well: the resistance goes up every bit the filament heats upwards. This makes the bulb self-regulating, which was a central factor in its adoption back in the day. If the bulb gets a tiny fleck hotter, the resistance goes up, the power drops, and the bulb cools. If the bulb gets a tiny fleck colder, the resistance goes down, the power increases, and the bulb warms up. So the seedling stays at a abiding T, which means a constant R and a constant P.
Or, information technology would if it was driven with DC current instead of AC.If the bulb gets a tiny scrap hotter, the resistance goes up, the ability drops, and the seedling cools. If the bulb gets a tiny bit colder, the resistance goes down, the ability increases, and the bulb warms upward. So the bulb stays at a abiding T, which means a constant R and a constant P.
Incandescent (Tungsten) bulbs are referred to equally https://support.industry.siemens.com/cs/document/24176167/what-is-the-pregnant-of-the-lamp-load-specification-in-digital-modules-?dti=0&lc=en-WW - in dissimilarity to Ohmic or inductive loads.
"seems like" is not a description that suits any Physical discussion.A short circuit is merely a conceptual idea which makes information technology possible to get reasonable answers out of excursion calculations.seems similar a blank piece of wire thereby making a short-circuit
No pieces of tungsten take anything like Zero Resistance. Resistance can be as low as you care to make information technology by using a short plenty and fat enough piece. The last affair you lot can beget to be is 'intuitive' when it comes to Electricity (or any other Physics, for that affair). It's really a chip disrespectful of the topic. No one managed to make Electricity practice what they wanted until they learned that they absolutely take to exercise some formal sums first.
If anyone's Dad starts to become lairy about Science (and they sometimes exercise) they just need to be given an elementary text book. The just valid answers to that sort of opinion involve demanding the 'dad' character makes the effort of learn basics.
My Grandad embarrassed me deeply with his level of ignorance of Science (he expected to hear the Satelloon passing overhead) - but I was a teenager at the time. I forgave him, of course.
There were several more replies, some fanciful nearly a million lightbulbs, etc. The number and tone of these replies (at least I felt) were over the height. Vanadium suggested the OP was not following the discussion, and I tin can run into why this feeling would be justified. I do non recollect the physics forum should be a place where a simple question should be met treating it in a glib, or hostile way. This brings me to the last note by centaur.
Sophiecentaur, your tone is more hostile than the rest, and I could non let it go by without annotate.
I know I was told in school the lightbulb filament has very low resistance, what is wrong with the logic that hooking the lightbulb up to 110 Five would deliver a lot of amps. "Seems similar" is advisable for any discussion. Hooking a battery directly with a piece of wire is likely to destroy the battery, and in full general parlance this is known as a "short circuit". Forgive us, if the wire really had some resistance and the circuit was non "perfectly" brusk in the mathematical sense.
Equally far equally the idea that, "No one managed to make Electricity practice what they wanted until they learned that they admittedly have to practice some formal sums kickoff.", millions of people do just that.
Personally, when I was eight-9 years one-time, I had wires controlling electricity, lighting lights, ringing bells, motors running with cars racing at variable speeds along tracks, without doing formal sums first. I doubtable others have too.
Maybe I missed something, but when a poster asks something on the forum with a reasonable question, he or she is entreating us to assist with the reply. I know in many posts, the answer they are given is, read wikipedia, or read an uncomplicated textbook. This is really unnecessary. I can envision many friends and relatives that would wonder about the same question as the OP and would have been satisfied early on with the answers without being told the answer requires days weeks or months of study.
Now I know that I personally in one case answered a mail on this forum with impatience, and I let it show. I suspect SCentaur did the same. I think many earlier posts by SC were helpful and look forward to later ones.
That thing bated looking at other folds in the forum
Other replies I have seen as well referred the affiche to wikipedia or elementary textbooks for answers. This is sometimes appropriate, but sometimes it is unhelpful and unmotivating.
Today, Thanksgiving, I wanted to discover out how long to cook a turkey. It was easier to ask my sister on the phone, than to read a cooking recipe. Hutchphd did a really proficient job explaining that the resistance of the filament increases as it heats upward. And he added the tease to motivate further investigation
That's the physics. You lot can put in the verbal numbers if you care.
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Well yeah it was. But I was being "hostile" on the OP's behalf. His Dad was the one who needs some 'redirection' in his attitude.Sophiecentaur, your tone is more hostile than the rest, and I could non let it go by without comment.
Cheers, the rest of y'all for assuasive me to be a scrap over-grumpy at times.
+aneOther replies I have seen also referred the poster to wikipedia or simple textbooks for answers. This is sometimes appropriate, but sometimes it is unhelpful and unmotivating.
There is zippo less helpful than a postal service that consists just of a link. People who inquire question on PF come up from a wide variety of backgrounds and some sort of conversation with posters is necessary if we want to come upwardly with an appropriate (helpful) respond. A lazy question will always be revealed somewhen.
Well yes it was. Simply I was being "hostile" on the OP's behalf. His Dad was the one who needs some 'redirection' in his attitude.Cheers, the balance of you for allowing me to be a bit over-grumpy at times.
I understand what yous are saying a bit. But nosotros should non make also many assumptions about "fathers".
My father was born in 1920, and fought in WWII. When computers came out and Wikipedia, he was already very elderly. My father and uncles would ask me a question, (being a physicist), and information technology would have been purposeless to tell them to await elsewhere.
Being able to reply their questions was one of the reasons they were then supportive of educating me.
They explained when WWII ended, the GI bill was generous in assuasive them farther schooling, (and many of that generation went) but they were now in their mid to late 20's and wanted to get married and raise a family. Nosotros all have to make choices.
That perhaps why I was sensitive to the thread
My Dad was built-in in 1923 and also served in WW2 so I know where you are coming from. He did several EE courses at night schoolhouse and concluded up both working and learning. His choice and he ended up as a pretty well rounded Engineer. Perhaps the systems in our 2 different countries afforded different opportunities then I may non comparing like with like.My father was built-in in 1920, and fought in WWII.
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100 Watt Light Bulb Amps,
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