Energy & Electricity in Science : How Does a Light Bulb Work?

Energy & Electricity in Science : How Does a Light Bulb Work?


Hi, I’m Steve Jones, and I am going to tell
you how a light bulb works. Well, first of all we have to see the construction of the
light bulb. In fact, the working part is what we call a filament which is a thin piece of
metal, and this gets white hot. It glows very, very hot, and of course, if it was in the
air it would actually burn away. So, we enclose this in a bulb of glass which is sealed with
a screw thread on here to attach it to the place it’s being put, and we have two legs
here on which we hang the filament. These are usually tungsten. The electricity comes
in at one connection here at the bottom in the middle, and it goes up through here through
the wire, and then down and comes out through the screw thread at the side, or sometimes
we’ve got what’s called a bayonet connection. It depends on which country you’re in. Either
a screw thread or a bayonet. A bayonet is just flat. You push it in, and turn it, and
it jams. So, the glass bulb is evacuated; that is, there is no air in here. If there
were air in here this, as soon as it got hot, would burn away. You don’t want that. What
you do is you put in a gas which won’t allow burning. You remove the oxygen in here, and
you put in argon gas, so this contains argon and won’t burn so this can become white-hot
and it will produce mainly light. Well, not mainly light, actually, about ten percent
is light. Most of it is heat, and this glass bulb will get very hot. Normally, these bulbs
have a power of around sixty watts, so the sixty watts is a an average. They, in fact,
go from something like twenty five watts up to two hundred and fifty watts. A two hundred
and fifty watts lamp will actually use a current of one ampere. A twenty five watt, of course,
will produce, will use a tenth of an amp. So, there we have an electric light bulb and
how it works.

16 thoughts on “Energy & Electricity in Science : How Does a Light Bulb Work?

  1. Thanks im grade 6 and im doin a project on electricity and this helped big time! andi learnt alot about it 5 out of 5 subscribed and liked

  2. thanks a nice explanation but actually i would like to have a farther physical explanation let s say using the black body spectrum and quantum leap…but thanks

  3. @ u235u235u235
    "he didn't explain how the heated metal takes the electricity and throws off photons."

    I am no expert on this (which is why I'm watching this video)…but… the First Law of Thermodynamics = Energy can be neither created nor destroyed, only converted to another state…. what's happening (I assume) is that the filament is a resistor; IE, it is "resisting" the current of electricity. when this happens, the energy of the current is converted into "convective" energy (or heat) which manifests as visible light, or photons…. a photon is the force carrier of the electromagnetic force (electricity, magnetism, light, heat, etc)……….  I guess the reason he didn't explain it is because that's getting into the realm of quantum physics, which isn't really necessary to explain the inner mechanisms of a light bulb (and requires a LOT more explanation)

  4. +is 0,,,,,only (——–)> ,,,,,+-(+)+-=-+,,,,,,,And -+=angry,,,,its means light,,,,,in my theory+is (0),,,,the light only dipand 100%,,,on (-) ,,,i have a theory without (-) people can't reachd or can't get the sun light,,,we need to use our (-)100% then we will get the sun light ,,,

  5. this explanation is better, then what i got from a coworker. he made it sound, like any gas, like methane would work. the problem with methane, is it burns at two thermal units, higher then argon, neon, hydrogen or nitrogen. it would heat up, warming the glass, softening it and melting the bulb.

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