A ray of light travelling in air is incident at angle of incidence, i
≈90o on a long rectangular slab of a transparent medium of thickness
y0. The medium has a variable refraction index of
μ(x)=√1+e2x/a ∀ x ≥ 0, where a is a positive constant. If
y0=a2, then
x coordinates of the point where the ray intersects the upper surface of the slab-air boundary is a
ln (N). Find the value of
N .
