For what position of the object does a convex lens form an erect and virtual image?

Where in front of the concave mirror should an object be placed to get its virtual and erect image?

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

Define the following terms in relation to a concave spherical mirror (any five):
$(i)$ Pole
$(ii)$ Centre of curvature
$(iii)$ Radius of curvature
$(iv)$ Principal axis
$(v)$ Principal focus
$(vi)$ Aperture
$(vii)$ Focal length

State the laws of refraction. Explain the phenomenon of refraction when a ray of light passes through a rectangular glass slab with the help of a ray diagram.

An object is situated at $8 \, cm$ from a convex lens of focal length $10 \, cm$. Find the position and nature of the image. Draw a ray diagram to illustrate the formation of the image (not to scale).