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Why is the squared meters negative?

  1. Apr 2, 2015 #1
    I work in energy auditing. I noticed a lot of the standards I am given for lighting, etc are in Watts per negative square meter: W·m-2.

    Does anyone know what this means? Why isn't it just in W·m2 ?
  2. jcsd
  3. Apr 2, 2015 #2


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    Science Advisor
    Gold Member

    ##a^{-n}## means the same as ##1/a^n##

    Anything raised to negative power is the same as a fraction with the thing being in the denominator.

    So what does ##Wm^{-2}## mean?
  4. Apr 2, 2015 #3


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    Staff: Mentor

    The dot between the w and the m is times, not divided by. I'm not sure why you would write it that way, but W·m-2 = W/m2
  5. Apr 2, 2015 #4
    Yes, this all makes sense now. Can't believe I didn't realise that one -_- . I don't know why, but the standards are just always written like that W·m-2.
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