JEE Main 2004 — Optics

A plane convex lens of refractive index $1.5$ and radius of curvature $30 \mathrm{~cm}$ is silvered at the curved surface. Now this lens has been used to form the image of an object. At what distance from this lens an object be placed in order to have a real image of the size of the object?

A light ray is incident perpendicular to one face of a $90^{\circ}$ prism and is totally internally reflected at the glass-air interface. If the angle of reflection is $45^{\circ}$, we conclude that the refractive index $n$ 

The maximum number of possible interference maxima for slit-separation equal to twice the wavelength in Young's double-slit experiment is

The angle of incidence at which reflected light totally polarized for reflection from air to glass (refractive index $n$ ), is