A light ray in air is represented by the incident vector I=3^−4^+12k^. It strikes a perfectly reflecting plane surface whose unit normal vector is n=k^. The ray is reflected back into air.
(i) Show that I is not a unit vector and obtain the corresponding unit incident vector Iu.
(ii) Calculate the unit vector Ru that gives the direction of the reflected ray.
(iii) Find the angle of incidence of the ray on the mirror.