Waves

Page
5

Object

© 2000 D. L. Power

Slide 39

LIGHT & ITS USES: Lenses

Convex Lenses

Ray Tracing

Two rays define an image

Ray 2: Light ray comes from top of object & travels through center of lens.

Ray #1

Ray #2

© 2000 D. L. Power

Slide 40

LIGHT & ITS USES: Lenses

Concave Lenses –

Lens that is thicker at the edges and thinner in the center.

Diverges light rays

All images are erect and reduced.

© 2000 D. L. Power

Slide 41

How You See

Near Sighted – Eyeball is too long and image focuses in front of the retina

Far Sighted – Eyeball is too short so image is focused behind the retina.

© 2000 Microsoft Clip Gallery

© 2000 Microsoft Clip Gallery

Slide 42

Light & uses: Lenses

Concave Lenses –

Vision – Eye is a convex lens.

Nearsightedness – Concave lenses expand focal lengths

Farsightedness – Convex lenses shortens the focal length.

Slide 43

Light & uses: Optical Instruments

Cameras

Telescopes

Microscopes

© 2000 Microsoft Clip Gallery

© 2000 Microsoft Clip Gallery

© 2000 Microsoft Clip Gallery

Slide 44

LIGHT & USES: Optical Instruments

LASERS

Acronym: Light Amplification by Stimulated Emission of Radiation

Coherent Light – Waves are in phase so it is VERY powerful & VERY intense.

Slide 45

LIGHT & USES: Optical Instruments

LASERS

Holography – Use of Lasers to create 3-D images

Fiber Optics – Light energy transferred through long, flexible fibers of glass/plastic

Uses – Communications, medicine, t.v. transmission, data processing.

Slide 46

Light & uses: Diffraction

Diffraction – Bending of waves around the edge of a barrier. New waves are formed from the original. breaks images into bands of light & dark and colors.

Refraction – Bending of waves due to a change in speed through an object.

Slide 47

LIGHT & USES: Diffraction

A diffraction grating. Each space between the ruled grooves acts as a slit. The light bends around the edges and gets refracted.

© 2000 Microsoft Encarta

Slide 48