In an experiment with a rectangular glass slab, for an angle of incidence of `60^@` in air, angle of refraction is measured to be `r_1`. When the glass slab is replaced by a hollow slab filled with water, angle of refraction is measured to be `r_2`. Show that `r_2 gt r_1`. Justify your answer.

Explanation

Here, `i=60^@, r=r_1`
According to Snell's Law
`.^(air)mu_(glass)=(sin i)/(sin r_(1))=(3)/(2)`
`sin r_(1)=(2)/(3) sin i=2/3 sin 60^@ =2/3 (sqrt3)/2 =1/(sqrt3)=0.577`
When glass slab is replaced by hollow slab filled with water, then according to Snell's Law,
`.^(air)mu_(water)=(sin i)/(sin r_(2))=4/3`
`sin r_2 =3/4 sini=3/4 sin 60^@ =3/4 (sqrt3)/2 = (3sqrt(3))/(8)=0.649`
As `sin r_(2) gt sin r_1 :. r_2gtr_1`