Which of the following is the lens formula?

When an object is placed between the principal focus $(F)$ and the pole $(P)$ of a concave mirror,what kind of image is formed?

The refractive indices of turpentine oil,kerosene,and alcohol are $1.47, 1.44$,and $1.36$ respectively. Based on this information,complete the following ray diagrams to show the path of a ray of light through each medium. (Give a reason for your answer.)

The power of a lens is $5$ dioptre. What is the focal length of the lens (in $m$)?

The magnification of a real image formed by a concave mirror is always ...

$(a)$ Write one use of a concave mirror as well as a convex mirror.
$(b)$ Draw ray diagrams for the following cases when a ray of light:
$(i)$ passing through the centre of curvature of a concave mirror is incident on it.
$(ii)$ parallel to the principal axis is incident on a convex mirror.
$(iii)$ is incident at the pole of a convex mirror.
$(iv)$ passing through the focus of a concave mirror is incident on it.