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What is this quantity called?

  1. Sep 27, 2010 #1
    If you take the Flux of a light source and multiple by the area of your detector you are left with a quantity in units of only watts.

    Now this is technically "power", but what is the correct term for this quantity?
  2. jcsd
  3. Sep 27, 2010 #2
    Are you talking about luminosity?

    Luminosity is a function of the amount of light output (brightness or flux) per given unit of surface area multiplied by the total surface area.

    L= b*((d^2)*pi*4)

    L=luminosity (watts)
    b=brightness or flux ("watts/meters^2")
    d=diameter of star (meters)
    ((d^2)*pi*4)=surface area (meters^2)

    It's basically the surface area (m^2) of the sphere multiplied by the brightness per unit of area. Which finds the total output (commonly shown in the form of watts.).
    Last edited: Sep 27, 2010
  4. Sep 27, 2010 #3
    No, because luminosity describes the total amount of energy emitted by an object.

    I'm talking about multiplying the apparent brightness of an object by the area of a detector to get the total amount of energy per second falling on that detector. I believe there is a certain term for this that is not "power" but I don't know what that term is.
  5. Sep 27, 2010 #4
    I think you're talking about "radiant flux" if you are talking about the amount per surface area unit per second observed by a detector.
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