Both a spherical mirror and a thin spherical lens have a focal length of $-15 \; cm$. What type of mirror and lens are they?

Under which of the following conditions can a concave mirror form an image larger than the actual object?

$(a)$ Draw a ray diagram in each of the following cases to show the position and nature of the image formed when an object is placed:
$(i)$ Between the focus and the centre of curvature of a concave mirror.
$(ii)$ Between the focus and the pole of a concave mirror.
$(iii)$ Between the centre of curvature and infinity for a concave mirror.
$(b)$ Give mathematical formulae for determining the magnification produced by a spherical mirror. What does $m = -1$ signify? Identify the mirror that can produce it.

Write down the equation connecting the object distance,image distance,and focal length of lenses and mirrors.

$A$ spherical mirror and a thin spherical lens have each a focal length of $-15\,cm$. The mirror and the lens are likely to be

Which type of mirror can produce a virtual image?