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Bulb in a vacuum?

  1. Nov 24, 2015 #1
    the question was: if a elliptical shaped bulb , which was covered from outside and internally reflected light in the bulb itself . what would happen if it were placed in a vacuum ? would it emmit light for eternity ?
    hope someone would shed some light on the matter ?:) , and explain this to a laymanlike myself? all observation and theories are welcome .

  2. jcsd
  3. Nov 24, 2015 #2


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    Staff: Mentor

    Welcome to PF!

    I'm not really sure of your logic, but if it is covered, it wouldn't emit anything, would it? Anyway, since no reflectors are truly perfect, it would quickly absorb and dissipate the light.
  4. Nov 24, 2015 #3
    Several things are not clear. Why the elliptical shape? What do you mean by covered from outside? With what? Why should it internally reflect light on itself? The last question makes it sound like a contradiction of something, where there should be none. A light bulb will not emit anything unless energy is supplied from a voltage source.
  5. Nov 24, 2015 #4


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    2017 Award

    Staff: Mentor

    Plus: How does the placement in a vacuum come into play? It would probably get broken sooner because of its heat.
  6. Nov 24, 2015 #5
    I think this a version of a thought experiment where you have a hollow sphere, with perfectly reflecting walls, and you trap light inside. Will the light be bouncing back and forth from the walls forever? Can you confirm this, Acemace?
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