The critical angle for light going from medium '$$x$$' to medium '$$Y$$' is $$\theta$$. The speed of light in medium '$$x$$' is '$$V$$' . The speed of light in medium '$$Y$$' is

A biconvex lens $$\left(R_1=R_2=30 \mathrm{~cm}\right)$$ has focal length equal to the focal length of concave mirror. The radius of curvature of concave mirror is [Refractive index of material of lens $$=1.6$$ ]

The critical angle for light going from medium A into medium B is $$\theta$$. The speed of light in the medium A is $$\mathrm{V}_{\mathrm{A}}$$. What is the speed of light in the medium $$\mathrm{B}$$ ?

The refractive index of glass is 1.5 and that of water is 1.33 . The critical angle for a ray of light going from glass to water is