Specular and diffuse reflection
Reflection angles are measured from the local normal.
Key knowledge
For a ray reflected from a locally planar stationary isotropic interface, the incident and reflected rays and surface normal share a plane, with θ_r=θ_i. A smooth surface can give a specular reflected pattern; varying local normals on a rough surface spread directions into diffuse reflection. Reflection and absorption/transmission fractions are separate questions.
Values and equations
θ_r=θ_i
- θ_r,θ_i
- Reflection and incidence angles from the local normal rad
Conditions and scope
- Geometric-optics regime and angles measured from the local surface normal, not the surface itself.
- Roughness relative to wavelength, scattering and material response determine applicability. The direction rule does not establish unit reflectance or a universal intensity distribution.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read §1.2 law1.1, local-normal geometry and smooth/rough-surface figures1.5–1.7. The record covers direction rather than Fresnel amplitudes or every scattering surface.
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Entry details
Permanent link to this entry ↗- Record identity
- foundation-physics-specular-reflection
- Revision
- foundations-refresh.1
- Structured reference record
- Foundational reference additions