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Elastic Wave Reflection
P and S waves at an interface — Zoeppritz equations and critical angle
Snell's Law: sinθ₁/V₁ = sinθ₂/V₂. When V₂ > V₁, a critical angle θ_c = arcsin(V₁/V₂) exists — beyond this, total internal reflection occurs. Seismologists use these principles to image Earth's interior. The Zoeppritz equations give exact reflection (R) and transmission (T) coefficients for P-P, P-S, S-P, and S-S conversions at layer boundaries, forming the basis of seismic reflection surveys.