Total internal reflection is when a light ray cannot refract past a boundary and stays inside the first material $-$ this angle is called the critical angle, any incident angle larger than the critical angle turns into a reflection $-$ a total internal reflection as shown above. If a glucose solution in water has a refractive index n$1$ of $1\mathrm{.}38$ and the air above it has a refractive index of $1\mathrm{.}00,$ what is the critical angle in degrees?