Which type of lens magnifies - convex or concave?

Answer

Convex are thicker in the middle and thin out at the edges. These lenses magnify and are used for reading glasses and to correct long-sightedness (hyperopia).

Concave lenses are thin in the middle and thick towards the edges. These lenses shrink things and are used to correct short-sightedness (myopia).

A good example of this is to take a spoon and look at your reflection in it. Looking at the concave side of the spoon (the front) will make you look smaller, looking at the convex side of the spoon (the back) will make you look bigger.

Answer

A concave mirror can magnify.

Convex mirrors always shrinks things. They are used sometimes in offside rear vision mirrors for vehicles. A concave mirror will also shrink things if you look at the mirror from far enough away and the object you look at is also far away (but you wouldn't want to use it for a rear vision mirror because it then also turns stuff upside down).

Concave lenses disperse light rays outward, rendering it impossible for them to focus incoming light onto a plane surface. Their "focus" is virtual, behind the lens on the side of the light source. If the concave surface is used as a reflector, it will form a real image. This is the basis for reflector telescopes.

Further info: http://en.wikipedia.org/wiki/Lens_(optics)

First answer by ID1175531071. Last edit by Quirkyquantummechanic. Contributor trust: 2579 [recommend contributor]. Question popularity: 24 [recommend question].