An optics experiment is set up to study how the angle of refraction of light inside a crown glass block varies with the angle of incidence.
Table 1 shows the experimental results.
| Angle of incidence (degrees) | Mean angle of refraction (degrees) |
|---|---|
| 20 | 13 |
| 40 | 25 |
| 60 | XXX |
| 80 | 41 |
For an angle of incidence of 60∘60^\circ60∘, the student recorded the following three measurements for the angle of refraction: 34∘,37∘,34∘34^\circ, \quad 37^\circ, \quad 34^\circ34∘,37∘,34∘ Calculate the mean value X X\,X 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 20∘ 20^\circ\,20∘ and 80∘80^\circ80∘?
The student wants to compare the refraction caused by the crown glass block with that of a flint glass block. Which variable must the student keep the same for both blocks to ensure a fair comparison?