Two transparent media A and B are separated by a plane boundary. The speed of light in those media is 1.5 × 108 m/s and 2.0 × 108 m/s, respectively. The critical angle for a ray of light going from medium A to medium B is:

In a concave lens, a ray of light emanating from the object parallel to the principal axis of the lens, after refraction:

A ray of light incident at an angle θ on face AB of a prism of refractive index 1.5 emerges normally from its face AC. If the angle of the prism is 5°, the angle of incidence θ should be nearly: