Secondly, the iris blocks light from hitting the extreme edges of the crystalline lens. Why might an eye want to block the light hitting the extreme edges of a lens? What is the name for the effect when light does hit the edges of a lens? Can you understand why a person’s vision is blurred when they get their eyes dilated at the doctor?

A nearsighted person has a near point of 20 cm and a far point of 40 cm. What refractive power lens is necessary to correct this person’s vision to allow her to see distant objects?A. -5.0 D         B. -2.5 D         C. +2.5 D         D. +5.0 D

1. Consider a cuboid made of crown glass which has inner space filled with water. A ray of light is incident onto the 10 cm thick block of glass on the top face of the cuboid at 60◦ from the normal. It then meets the glass-water boundary and is refracted again and continues through a water thickness of 5 cm before reaching another water-glass boundary. The ray of light is again refracted and continues in the 10 cm thick block of glass on the base of the cuboid and eventually exits into air. (a) Draw a clearly labelled diagram of the path the ray of light takes. (b) Calculate all the angles of refraction and incidence at each boundary. (c) Calculate the optical path of the ray of light from the point it is incident on the surface of the cuboid to the point it exits into air on the other end.

A 45°-90°-45° prism is constructed from a synthetic resin. As shown in the figure, a light beam that enters the prism at the midpoint of the long side and parallel to the base exits the prism at an angle of 33° below the horizontal. What is the index of refraction of this prism? Additional Materials