1. A ray of light is incident on a piece of glass at an angle of 45.0°. If the angle of refraction is 25.0°, find a. the refractive index and b. the critical angle. c. Solve (a) and (b) graphically 2. A hollow glass cell is made of thin glass in the form of an equiconcave lens. The radii of the two surfaces are 1.650 cm, and the distance between the two vertices is 1.850 cm. When sealed airtight, this cell is submerged in water of index 1.3330. Calculate a. the focal lengths of each surface and b. the power of each surface. 3. Three lenses with focal lengths of +8.40, -4.60, and +6.20 cm, respectively, are located one behind each other in this order and 2.0 cm apart. a. If parallel light is incident on the first lens, how far behind the third lens will the light be brought to a focus?