1. Chapter 29 Light Waves

2. Huygens’ Principle Every point on a wave front can be regarded as a new source of wavelets, which combine to produce the next wave front, whose points are sources of further wavelets, and so on. Plane Waves

3. Huygen’s Principle can be used to explain the propagation of wave fronts involved in reflection, refraction, and diffraction.reflection, refraction

4. 2.DIFFRACTION The bending of light that passes around an obstacle or through a narrow slit, causing the light to spread and to produce light and dark fringes. Double Slits Single Slit

6. Diffraction Notes Long wavelengths bend a great deal around small objects. Because of diffraction AM radio waves may be received better than FM radio waves. Microscopy diffraction limit - One cannot see details of objects that are approximately the same size as or smaller than the wavelength of the illuminating light.

7. 3.INTERFERENCE Two point sources Demo - Finger slit interference Demo - Single-Color Thin Film Interference

8. Soap Bubbles

9. Interference Colors by Reflection from Thin Films Iridescence - the phenomenon of seeing colors by interference in thin films. Demo - Soap bubbles and pipe Example - Coated photographic lenses Demo - Peacock feathers Interferometers measure small distances.

10. 4.POLARIZATION Common sources of light are not polarized. Polaroid Crystals - one axis direction absorbs, one transmits. Polarized glare occurs on reflection from nonmetallic surfaces. Polarization Demo

11. COLORS BY TRANSMISSION THROUGH POLARIZING MATERIALS Demo - Polaroids and accessories Sunglasses

12. Three-Dimensional Viewing Stereoscopic viewers

13. Teapot Stereogram

14. 5.HOLOGRAPHY Hologram means whole message. Demo - Reflection hologram Demo - Transmission hologramTransmission hologram No lenses are used to create nor to view a hologram.

15. Holography Notes Object and source both illuminate all of the photographic plate. The light used to make the hologram must be coherent. A hologram is an interference pattern.

16. More Holography Notes It is best to use coherent light when viewing a hologram. A hologram can be divided. One gets a magnified holographic image by viewing a hologram with a longer of light than was used in creating the hologram.

17. Chapter 29 Review Questions (a) AM waves travel faster than FM waves (b) AM wavelengths are shorter than FM wavelengths (c) AM waves are scattered more than FM waves (d) AM waves are diffracted more than FM waves AM band radio waves travel farther than FM band radio waves because (d) AM waves are diffracted more than FM waves

18. If laser light passes by a hair, a pattern of light and dark can be seen on a properly placed screen. What phenomenon (phenomena) is (are) being observed? (a) diffraction (b) polarization (c) chromatic aberration (d) all of the above (e) none of the above (a) diffraction

19. Polaroid sunglasses worn in a normal viewing position will eliminate polarized glare. (a) vertically (b) horizontally (c) all (b) horizontally

20. Two polaroids that have their polarization axes at 45 o to each other will still allow light to pass through. (a) True (b) False (a) True

21. The point where a soap bubble bursts will be black just as it bursts. (a) True (b) False (a) True