In fiber optics light rays beamed into a fiber can propagate within the core for great distances with remarkably little reduction in intensity due to this condition.  
In fiber optics light rays beamed into a fiber can propagate within the core for great distances with remarkably little reduction in intensity due to this condition.  It can only occur when going from a medium of greater index of refraction to one of lesser index of refraction and only results for any angle of incidence greater than "theta sub C."  Evidenced in halos and rainbows, FTP, name this phenomenon where all the light incident on a boundary is reflected back into the original material.
In fiber optics light rays beamed into a fiber can propagate within the core for great distances with remarkably little reduction in intensity due to this condition.  
total internal reflection