Incident light angle brightness

AI Thread Summary
When light strikes a surface at varying angles, it appears darker at higher angles due to the cosine relationship between angle and brightness. The brightness does not change linearly with angle, as the intensity of light is influenced by the surface area the beam interacts with. The formula for brightness can be approximated using the cosine of the angle, reflecting how the effective area of light exposure changes. Additionally, the inverse-square law affects intensity, though its impact diminishes at greater distances from the light source. Understanding these principles is crucial for applications in lighting design and photography.
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when light hits a surface at an angle. it is darker if it hits it at higher angle(facing away) than at a lower angle(facing towards). 1


Is there a formula for the brightness.The relationship of angle to brightness does not look linear.


http://www.vam.ac.uk/vastatic/microsites/1384_leonardo/animated_illustrations/view/?movie=light" 1
 
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The brightness would go like cos of the angle.
 
Is this only because the greater the angle, the greater the surface area that the beam interacts with? Or are there other factors?
 
It is just that Intensity = Power/area
 
There is also an inverse-square dependence, which is negligible if (for example) a point-like source is very far from the surface.
 

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