After tracing the path of a ray of light passing through a rectangular glass slab for four different values of the angle of incidence, a student reported his observations in tabular form as given below :
S.No | <i | <r | < e |
I | 300 | 190 | 290 |
II | 400 | 280 | 400 |
III | 500 | 360 | 500 |
IV | 600 | 400 | 590 |