Lenses

Convex lens

Convex lens: Thicker in the middle, converges light rays to a real focus, can form both real and virtual images. Concave lens: Thinner in the middle,

Principal focus (F) is the point

Principal focus (F) is the point where parallel rays converge (convex) or appear to diverge from (concave) after refraction. Focal length (f) is the d

For ray diagrams

For ray diagrams: (1) Ray parallel to optic axis passes through focus after refraction, (2) Ray through optical center passes straight, (3) Ray throug

1/f = 1/v

1/f = 1/v - 1/u, where f = focal length, v = image distance, u = object distance. Alternative form: f = uv/(u+v). Must use Cartesian sign convention:

m = hi/ho = v/u

m = hi/ho = v/u, where hi = image height, ho = object height. Positive magnification indicates erect image, negative indicates inverted. |m| > 1 means