Difference between convex lens and concave lens?

Question

Give four differences between a convex lens and a concave lens.

Answer 1

Four?

One is enough.

A concave lens is thinnest in its middle (the point where the line between the two focal points intersects the lens (at right angles to the plane of the lens).

A convex lens is thickest in its middle.

A convexo-concave lens is concave on one side and convex on the other.  Virtually all spectacle (eye glasses) lenses are like this.  Whether the particular lens is convex or concave is answered by the thickness at it middle compared with elsewhere on the lens.

You can also consider all the combos: single (the other side is flat), double convex and concave.

Then, if you really wanted to know some of the PROPERTIES of these lenses, then you get a number characteristic differences - let us now, and someone will elaborate.

Answer 2

Concave lenses bend inwards like so  :   (

Convex bend outwards like so:    )

Reflections in concave (like on a spoon) turn upside down.

Reflections in convex do not (it might be the other way round, get a spoon and look in it)