An incident ray falls normally on a glass slab. What is the angle of refraction (in $°$)?

Draw ray diagrams showing the image formation by a concave mirror when an object is placed:
$(a)$ Between pole $(P)$ and focus $(F)$ of the mirror.
$(b)$ Between focus $(F)$ and centre of curvature $(C)$ of the mirror.
$(c)$ At centre of curvature $(C)$ of the mirror.
$(d)$ $A$ little beyond centre of curvature $(C)$ of the mirror.
$(e)$ At infinity.

Which type of image cannot be obtained by a concave mirror?

$A$ light ray enters from medium $A$ to medium $B$ as shown in the figure. The refractive index of medium $B$ relative to $A$ will be

Define lateral magnification.

How are power and focal length of a lens related? You are provided with two lenses of focal length $20\, cm$ and $40\, cm$ respectively. Which lens will you use to obtain more convergent light?