Describe the optical phenomena illustrated in the diagram (a) and label the rays and lines shown in (b). Estimate the angles i, r, a, and b.

a)
A: Refraction
B: Reflection

b)
I: Incident ray
II: Refracted ray
III: Normal
IV: Reflected ray
V: Mirror (or Reflecting surface)

c)
To measure the angles, we use a protractor on the diagram. Based on visual estimation:
$i$: $\boxed{\text{42}\degree}$
$r$: $\boxed{\text{28}\degree}$
$a$: $\boxed{\text{30}\degree}$
$b$: $\boxed{\text{30}\degree}$