A student investigates how the angle of refraction of light in an acrylic block depends on the angle of incidence.
Table 1 shows some of the student's results.
| Angle of incidence (degrees) | Mean angle of refraction (degrees) |
|---|---|
| 15 | 10 |
| 30 | 19 |
| 45 | YYY |
| 60 | 35 |
For an angle of incidence of 45∘45^\circ45∘, the student's three measurements for the angle of refraction were: 27∘,29∘,28∘27^\circ, \quad 29^\circ, \quad 28^\circ27∘,29∘,28∘ Calculate the mean value Y Y\,Y to complete Table 1.
Complete the following sentence by choosing the correct word from the options: random, systematic, or zero.
"The student conducted three trials for each angle of incidence and calculated a mean to reduce the effect of __________ errors."
Using the data in Table 1, state whether the angle of refraction is less than, equal to, or greater than the angle of incidence.
Why is the student's conclusion only valid for angles of incidence between 15∘ 15^\circ\,15∘ and 60∘60^\circ60∘?
The student wants to compare the refraction caused by the acrylic block with that of a glass block. Which variable must the student keep the same for both blocks to ensure a fair comparison?