Give one use of a concave lens.

Which of the following can produce a magnification of $+5$ as well as $-5$?

The mirror outside the driver's side of a vehicle is usually a convex mirror. Printed on such a mirror is usually the warning "Vehicles in this mirror are closer than they appear". What is the reason for this warning?

$A$ plane mirror as well as a convex mirror can produce a real image if the object is virtual. How?

Find the position,nature,and size of the image of an object $3 \, cm$ high placed at a distance of $9 \, cm$ from a concave mirror of focal length $18 \, cm$.

$(a)$ Write the relation between $u, v, f$ for lenses and for mirrors,where $u, v, f$ are object distance,image distance,and focal length respectively.
$(b)$ The magnification produced by a concave mirror is $m = +4$. Write the information about the image given by this statement.
$(c)$ Draw a ray diagram for the following and show the formation of the images in the case of a concave mirror when the object is placed:
$(i)$ Between the pole and the focus point.
$(ii)$ At the centre of curvature.