Answer:
51.39°
Explanation:
i = Angle of incidence = 30.0°
r = Angle of refraction = 23.0°
Refractive index of the material is given by
[tex]n=\frac{sin\ i}{sin\ r}\\\Rightarrow n=\frac{sin30}{sin23}\\\Rightarrow n=1.27965[/tex]
Critical angle is given by
[tex]sin\theta_c=\frac{1}{n}\\\Rightarrow \theta_c=sin^{-1}\frac{1}{1.27965}\\\Rightarrow \theta_c=51.39^{\circ}[/tex]
The critical angle of the substance is 51.39°
