Mirrors and Lenses

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Slide 1

Optics

Mirrors and Lenses

Slide 2

Reflection

We describe the path of light as straight-line rays

Reflection off a flat surface follows a simple rule:

angle in (incidence) equals angle out (reflection)

angles measured from surface “normal” (perpendicular)

incident ray

exit ray

reflected ray

Slide 3

Reflection Vocabulary

Real Image –

Image is made from “real” light rays that converge at a real focal point so the image is REAL

Can be projected onto a screen because light actually passes through the point where the image appears

Always inverted

Slide 4

Reflection Vocabulary

Virtual Image–

“Not Real” because it cannot be projected

Image only seems to be there!

Slide 5

Virtual Images in Plane Mirrors

Slide 6

Hall Mirror

Useful to think in terms of images

mirror only

needs to be half as

high as you are tall. Your

image will be twice as far from you

as the mirror.

Slide 7

LEFT- RIGHT REVERSAL

AMBULANCE

Slide 8

Curved mirrors

What if the mirror isn’t flat?

light still follows the same rules, with local surface normal

Parabolic mirrors have exact focus

used in telescopes, backyard satellite dishes, etc.

also forms virtual image

Slide 9

Concave Mirrors

Curves inward

May be real or virtual image

View kacleaveland's map

Taken in a place with no name (See more photos or videos here)

"Have you ever approached a giant concave mirror? See your upside-down image suspended in mid-air. Walk through the image to see a new reflection, right-side-up and greatly magnified. In the background you see reflected a room full of visitors enjoying other

Slide 10

For a real object between f and the mirror, a virtual image is formed behind the mirror. The image is upright and larger than the object.

For a real object between f and the mirror, a virtual image is formed behind the mirror. The position of the image is found by tracing the reflected rays back behind the mirror to where they meet. The image is upright and larger than the object.