A student is conducting an experiment to investigate how light refracts when passing from air into a block of heavy flint glass. They measure the angle of incidence, iii, and the angle of refraction, rrr, for several trials.
The experimental data is plotted in Figure 1 below.
| Angle of incidence, iii (∘^{\circ}∘) | Angle of refraction, rrr (∘^{\circ}∘) |
|---|---|
| 10 | 6 |
| 20 | 12 |
| 30 | 18 |
| 40 | 23 |
| 50 | 28 |
| 60 | 32 |
| 70 | 35 |
Use the data and the trend in Figure 1 to estimate the value of the angle of refraction, rrr, when the angle of incidence, iii, is 80∘80^{\circ}80∘.