Why do we measure the angle of incidence or reflection

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SUMMARY

The measurement of the angle of incidence and reflection is conducted with respect to the normal to the surface rather than the horizontal surface due to the simplicity and clarity it provides in explaining optical phenomena. This approach is particularly effective for both flat and curved surfaces, such as spherical surfaces, where horizontal measurements would complicate the analysis and require numerous assumptions. By using the normal, the principles of reflection and refraction can be articulated more effectively, leading to a better understanding of light behavior.

PREREQUISITES
  • Understanding of basic optics principles
  • Familiarity with the concept of the normal line in geometry
  • Knowledge of reflection and refraction laws
  • Basic comprehension of curved surfaces in physics
NEXT STEPS
  • Research the laws of reflection and refraction in detail
  • Explore the concept of the normal line and its applications in optics
  • Study the behavior of light on curved surfaces
  • Investigate practical applications of these principles in optical devices
USEFUL FOR

Students of physics, optical engineers, and anyone interested in the principles of light behavior and its applications in various fields.

Alche
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Why do we measure the angle of incidence or reflection (or say refraction even) w.r.t normal to the surface and why not w.r.t the horizontal surface?
 
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Hi Alche! :wink:

I think it's because defining the angle a ray makes with a line (the normal) is easier than defining the angle it makes with a plane (the tangent plane, to a surface that may be curved). :smile:
 


Even I think the same. :smile:

I think we measure the angle with respect to the normal because by doing so we can explain many phenomenon that happens in the nature due to reflection and refraction of light.May be by measuring the angle horizontally we won't be able to explain those phenomenon so neatly. Or may be we'll be but only in the case of flat objects.

And in the case of reflection and refraction on spherical surface where surface is not horizontal we won't be able to explain all the things without having lots of assumptions.

So for keeping the things easy and clear we measure the angle w.r.t to normal.
 

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