Page 266 - Introduction to Continuum Mechanics

250 The Elastic Solid

That is, the reflected transverse wave has the same wavelength as that of the incident transverse
wave and the angle of reflection is the same as the incident angle, the longitudinal wave has a
different wavelength and a different reflection angle depending on the so-called "refraction
index n."
With cos (f>i dropped out, and in view of Eqs. (xiv) to (xviii), the boundary conditions (vii)
and (viii) now become

These two equations uniquely determine the amplitudes of the reflected waves in terms of the
incident amplitude (which is arbitrary). In fact