Optics: Mirrors and Lenses 2

Convex Mirrors Rays diverge so the image is virtual f is half of the radius of curvature

(negative) Image is virtual, erect and reduced Wide area reflected so used in

stores, rear view mirrors, side view mirrors (objects in mirror…)

Lenses Glass or Plastic or Polycarbonate with

n greater than 1 2 sides (faces) of the lens

Each side can be flat OR part of a sphere

Convex and Concave Lenses Convex

thicker at the center than the edgesConvergingRefract light rays so they meet

Convex and Concave Lenses Concave

Thinner at the center than the edgesDiverging

Covex Lens: Real Image 3 ray diagram – from top of object

First ray parallel to axis, then through focal point

Second ray through F’ then parallel to axisThird ray is through center of lens

Lens assumed very thin f depends on

Shape of lensn of lens material

Covex Lens: Real Image Beyond 2F – image real, inverted, and

reduced Approaching F – image real, inverted

enlarged At 2F image is at 2F – inverted, same

size

Covex Lens: Virtual Image

If the object is at F, ray emerge in a parallel beam

If the object between F and lens then the rays

DO NOT converge on opposite side of lensimage is virtual, erect and enlarged

Concave Lens: Virtual Image All rays diverge Virtual image is erect and reduced

Doesn’t matter how far object is from the lens

f is negative, corrects near sightedness