**Questions:**

1) Compare the two examples below by completing the diagrams by drawing in a series of wavefronts and a ray to represent the refracted waves:

a)

b)

2) Compare the two examples below by completing the diagrams by drawing in a series of wavefronts and a ray to represent the incident waves:

a)

b)

3) A ray of light travelling through air moves into a liquid medium and its speed decreases from c to 2.5 × 10^{8} m/s. Calculate the absolute refractive index of the liquid:

4) The diagram below represents three medium that a light wave passes through. Sketch the approximate path of the light wave as it travels across the three boundaries: