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Photons/Second from a 100W bulb.

  1. Jun 16, 2011 #1
    1. The problem statement, all variables and given/known data

    Estimate how many photons of visible light (500 nm) are emitted by a 100 W Bulb.

    The answer on the sheet says approximately 10[itex]^{20}[/itex] photons/second

    However when I work it out I get a slightly different answer.

    2. Relevant equations

    I used that 1J=1W/s or E=P/t

    Also Energy of one photon is E=hf so if you had lots of photons you would [itex]\Delta[/itex]E=nhf where n is the number of photons.

    3. The attempt at a solution

    I get 2.5[itex]\times[/itex]10[itex]^{20}[/itex] photons/second
  2. jcsd
  3. Jun 16, 2011 #2


    User Avatar
    Homework Helper
    Gold Member

    You solved the problem correctly.
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