Question

a) calculate the speed of light in the glassb) the angle of incidence, θ.c) the refractive index of the liquid.

Answer 1

a) Given that refractive index of glass is 1.5,

We know that speed of light in medium of refractive index n is given by,

`v=(c)/(n)`

In this case,

`v=(3*10^8)/(1.5)=2*10^8\text{ m/s}`

b) Using Snell's law at the air-glass interface,

`\begin{gathered} n_(air)sin\theta=n_(glass)sin15\degree \\ \Rightarrow sin\theta=1.5*0.2588 \\ \Rightarrow sin\theta=0.3882 \\ \Rightarrow\theta=22.84\degree\approx23\degree \end{gathered}`

c) Again applying Snell's law at the glass-liquid interface,

`\begin{gathered} n_(glass)sin60\degree=n_(liquid)sin90\degree \\ \Rightarrow1.5*0.866=n_(liquid) \\ \Rightarrow n_(liquid)=1.299\approx1.3 \end{gathered}`