An air bubble in water $$\left(\mu=\frac{4}{3}\right)$$ is shown in figure. The apparent depth of the image of the bubble in plane mirror viewed by observer is.

A fish in water (refractive index $$n$$ ) looks at a bird vertically above in the air. If $$y$$ is the height of the bird and $$x$$ is the depth of the fish from the surface, then the distance of the bird as estimated by the fish is

The critical angle of a medium having the refractive index $$\sqrt2$$ is :

When angle of incidence on one face of the equilateral glass prism is $$3 / 4^{\text {th }}$$ of the angle of prism, the ray of light undergoes minimum deviation. If the velocity of light in vacuum is '$$c$$' then the velocity of light in the glass is :