Chapter 18 Mirrors and Lenses

Objectives

• 18.1 Explain how concave, convex, and plane mirrors form images

• 18.1 Locate images using ray diagrams, and calculate image location and size using equations

• 18.1 Explain the cause of spherical aberration and how the effect may be overcome

• 18.1 Describe uses of parabolic mirrors

Objectives

• 18.2 Describe how real and virtual images are formed by convex and concave lenses

• 18.2 Locate the image with a ray diagram and find the image location and size using a mathematical model

• 18.2 Define chromatic aberration and explain how it can be reduced

• 18.2 Explain how optical instruments such as microscopes and telescopes work

Mirrors

• Plane Mirror: Flat, smooth surface where light is reflected by specular reflection and not diffuse

Flat Plane Mirror

• Image reversed Left-Right

• Image formed equal distance behind mirror

• Image is Virtual– Rays don’t converge

Real and Virtual

Real verse Virtual

• Since real images do converge, they can be projected onto a screen.

• Virtual images can not be projected, because rays don’t converge

Concave Mirrors

• Curved in• Focal point is where

parallel rays would converge– Always ½ curvature

Concave Mirrors/Convex Lens

Image Formed at Intersection

Convex Lens Formation

Convex Lens Formation

Convex Lens Formation

Convex Lens Formation

More on Eye

Spherical Aberration

• When the mirror/lens has defects which cause parallel rays NOT to converge at the focal point

• Mirrors tend to be easier to make more precise then lens due to size limitations of lens

Chromatic Aberration

• Due to light waves refracting differently, get blurred image at edges of lens

• To fight this, use two lenses, one of each, to cancel effects