CGPET 2021 Solved Paper

Given, refractive index for glass, aµg=

3

2

and refractive index for water, aµw=

4

3

Since, light ray tavels from glass (denser) to water (rarer).

So, the refractive index of glass with respect to Water is
wµg=

aµg

aµw

⇒wµg=

3 2

4 3

=

9

8

......(i)
If critical angle be ic, then
sinic=

1

µg

⇒sinic=

1

9 8

∴ ic=sin−1(

8

9

)