How much light passes through a window?

In summary: So, if the light source is isotropic, the amount of light through the window would be 1600 lumens. However, if we consider it as a sphere, the amount of light through the window would be 1600 lumens multiplied by the ratio of the window's area to the sphere's surface area, which is equal to (1600 lumens)*((0.015m^2)/(4*pi*(0.14m)^2)) = 0.0051 lumens. In summary, the amount of light through the window is 0.0051 lumens when considering the light source as a sphere.
  • #1
bobobano
4
0

Homework Statement


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.


Homework Equations


lux = lumens/m^2


The Attempt at a Solution


Since there's no material in the window, shouldn't it be the full 1600 lumens seen inside?
 
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  • #2
bobobano said:

Homework Statement


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.


Homework Equations


lux = lumens/m^2


The Attempt at a Solution


Since there's no material in the window, shouldn't it be the full 1600 lumens seen inside?

Welcome to the PF.

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
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
bobobano said:
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)

It is some area ratio, but on re-reading the question, maybe the light source is not isotropic? They mention a wall and a window, so I'm not sure whether to ratio the area of the window to the wall or to an isotropic sphere. Is there a picture that goes with the question, or else are you able to understand the question well enough to answer it now?
 
  • #5
I dropped him an e-mail and he says to consider it as a sphere.
 
  • #6
bobobano said:
I dropped him an e-mail and he says to consider it as a sphere.

Okay, so you know what to ratio then?
 
  • #7
yea.
 

What is light through a window?

Light through a window is the phenomenon of light passing through a transparent opening in a wall or structure, typically made of glass. This can occur naturally from sunlight or artificially from artificial lighting sources.

How does light pass through a window?

Light passes through a window due to the properties of transparent materials such as glass. These materials allow light to pass through them without significantly altering its direction or intensity.

What factors affect the amount of light passing through a window?

The amount of light passing through a window can be affected by several factors, including the transparency and thickness of the material, the angle of incidence of the light, and any obstructions or reflections in the path of the light.

Why does light appear different when passing through a window?

Light can appear different when passing through a window due to refraction, which is the bending of light as it passes through a transparent material. This can cause the light to appear distorted or to create rainbows when passing through a prism-like surface.

What are some applications of light passing through a window?

The most common application of light passing through a window is for natural lighting in buildings. This can save energy and provide a more comfortable environment for occupants. Other applications include using windows as solar panels to generate electricity and studying the properties of light in scientific experiments.

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