Distinguish between concave and convex mirrors.

How can you experimentally locate the principal focus of a concave mirror?

Where are the images formed in convex and concave lenses?

Draw diagrams showing image formation by a concave lens, indicating the optical centre, principal axis, principal focus, and focal length.

If you walk towards a plane mirror at a speed of $1.2 \mathrm{m}/\mathrm{s}$, how fast will you approach your image in the mirror?