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Light through a window 
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#1
Mar2111, 03:51 PM

P: 4

1. The problem statement, all variables and given/known data
A lamp producing 1600 lumens is 16" away from a window of 0.015m^2 on a wall 0.14m^2, what is the amount of light through the window. 2. Relevant equations lux = lumens/m^2 3. The attempt at a solution Since there's no material in the window, shouldn't it be the full 1600 lumens seen inside? 


#2
Mar2111, 04:28 PM

Mentor
P: 41,369

I think the point of the question is that the light source is isotropic, so only a fraction of the total light goes through the area of the window. How can you calculate the fraction of the total area that the window represents (hint  use the distance to the window for something...) 


#3
Mar2111, 04:41 PM

P: 4

am I correct in thinking that if I multiply the lux over the area, from the lamp to the window, by the window's area I'll get the lumens through the window?
Light through window = (light from lamp)/(pi*distance2)*(window surface area) 


#4
Mar2111, 04:50 PM

Mentor
P: 41,369

Light through a window



#5
Mar2111, 04:59 PM

P: 4

I dropped him an email and he says to consider it as a sphere.



#7
Mar2111, 05:12 PM

P: 4

yea.



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