Let There Be Light!

1. Explore the textual information below:

If light passes from one medium to another, refraction of light occurs. If light passes from a medium in which it propagates at a greater speed to a medium in which it propagates at a lesser speed, refraction to the perpendicular occurs. Thus the angle of refraction is smaller than the angle of incidence. If light passes from a medium in which it propagates more slowly to a medium in which it propagates more rapidly, then refraction from the perpendicular occurs. Thus the angle of refraction is greater than the angle of incidence.

2. For a better idea, see the simulation available at  ‪‪Bending Light 1.1.34 (colorado.edu). Play with the simulation. Gradually change all the parameters and observe the differences.

3. Solve the problems using the data in Table 1. Speed of light propagation in different media, your experience from the simulations and the given graph.

Task 1. Light rays 1 and 2 pass from air to water, and ray 3 from water to air. Plot the direction of the rays after they pass through the water.

1. Which ray is refracted to the perpendicular?
2. Which ray is refracted by the perpendicular?
3. Which ray is not refracted?

Task 2. Consider the values given in Table 3. The refractive index of spectral colours in a glass prism and solve the problems:

a. Light of which colour travels through the glass prism at the greatest speed and will therefore refract the least?

b. Light of which colour travels through the glass prism at the least speed and will therefore refract the most?

c. The diagram shows a glass prism into which white light enters. After passing through the prism, the white light is refracted and broken down into its individual components – we observe a colour spectrum of light. Write the names of the spectral colours for the numbers 1 to 7.