Find linear magnification in the given diagram.

If refractive index of water is $\frac{4}{3}$ then refractive index of unknown medium is:

An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of 

A virtual image three times the size of the object is obtained with a concave mirror of radius of curvature $36 \mathrm{cm}$. The distance of the object from the mirror is

A glass prism $(\mu =1.5)$ is dipped in water $(\mu =4/3)$ as shown in figure. A light ray is incident nromally on the surface AB. It reaches the surface BC after totally reflected, if