1. Water has an index of refraction of 1.333. What is the speed of light through it?

ans: 2.25 x10⁸ m/s; v = c/n.

2. A ray of light strikes a thick sheet of glass (n = 1.5) at an angle of 25 deg from the normal. Find the angle of the refracted ray within the glass with respect to the normal.

ans: 16 deg; arcsin[1.00*sin(25deg)/1.5].

3. A ray of light strikes a thick sheet of glass (n = 1.5) at an angle of 25 deg from the normal. Find the angle of the ray reflected off the glass surface with respect to the normal.

ans: 25 deg; angle of reflection = angle of incidence.

4. A monochromatic beam of light in air has a wavelength of 589 nm in air. It passes through glass (n = 1.52) and then through carbon disulfide (n = 1.63). What is its wavelength in the carbon disulfide?

ans: 361 nm; since v=c/n and f remains unchanged, w_CS2 = w_air/1.63.

5. A beam of light in air is incident on the surface of a rectangular block of clear plastic (n = 1.49) at an angle of 35 deg from the normal of the surface. The light beam passes through the block and re-emerges from the opposite side into air at what angle from the normal to that surface?

ans: 35 deg; after traveling through 2 parallel surfaces separating n₁ / n₂ / n₁, the light returns to the original direction.

6. As the angle of incidence is increased for a ray incident on a reflecting surface, the angle between the incident and reflected rays ultimately approaches what value?

ans: 180 deg; the reflection approaches the direction parallel to the surface.

7. Diamond has an index of refraction of 2.419. What is the critical angle for internal reflection inside a diamond that is surrounded by air?

ans: 24.4 deg; critical angle = arcsin(n_air/n_dia).

8. A fiber optic cable (n = 1.50) is submerged in water. What is the critical angle for light to stay inside the cable?

ans: 62.4 deg; critical angle = arcsin(n_water/n_fiber).

9. A certain kind of glass has index of refraction = 1.65 for bluish light and index of refraction = 1.61 for reddish light. If a beam of white light (containing all visible wavelengths) is incident at an angle of 30 deg, what is the angle between the reddish and bluish light inside the glass?

ans: 0.45 deg; the difference between two arcsin's.
arcsin[1.00*sin(30deg)/1.61] - arcsin[1.00*sin(30deg)/1.65].