Question #81661

1 Answer
Jan 3, 2018

The words concave and convex refer to the shape of the lens itself.

Explanation:

Very simply, the words concave and convex refer to the shape of the lens itself.

con·cave
/känˈkāv,ˈkänˌkāv/
adjective
#" "#having an outline or surface that curves inward like the
#" "#interior of a circle or sphere.

con·vex
/känˈveks,ˈkänveks/
adjective
#" "#having an outline or surface curved outward like the
#" "#exterior of a circle or sphere.

A concave lens, therefore, has a surface that curves inward. it can do so on one or both faces of the lens and the symbol for this type of lens is a line with inward pointing arrows on it:

These lenses cause parallel rays entering the lens to diverge when they exit. This causes the image to be smaller for the viewer looking through the lens.

A convex lens has a surface that curves outward. it can do so on one or both faces of the lens and the symbol for this type of lens is a line with outward pointing arrows on it:

enter image source here

These lenses cause parallel rays entering the lens to converge when they exit. This causes the image to be larger for the viewer looking through the lens - this is what we normally think of as magnification.