Ch 19 Light III Wave Properties of Light

Ch. 19 - Light III. Wave Properties of Light (p. 546 -550) Ø Reflection Ø Refraction Ø Diffraction Ø Interference

A. Reflection Normal ØReflection w when a wave strikes an object and bounces off incident beam reflected beam

A. Reflection ØLaw of Reflection w the angle of incidence equals the angle of reflection

B. Refraction ØRefraction w bending of waves when passing from one medium to another w caused by a change in speed • slower (more dense) light bends toward the normal • faster (less dense) light bends away from the normal SLOWER FASTER

B. Refraction ØRefraction depends on… w speed of light in the medium w wavelength of the light - shorter wavelengths (blue) bend more

B. Refraction ØExample: View explanation.

C. Diffraction ØDiffraction w bending of waves around a barrier w longer wavelengths (red) bend more opposite of refraction

D. Interference ØInterference w constructive brighter light w destructive dimmer light

E. Cool Applications! ØFiber Optics w Total Internal Reflection • when all light is reflected back into the denser medium

E. Cool Applications! ØThe “Broken Pencil” w refraction View animation and explanation of the “Broken Pencil. ”

E. Cool Applications! ØRainbows w refraction-reflection-refraction

E. Cool Applications! ØDiffraction Gratings w glass or plastic made up of many tiny parallel slits w may also be reflective w spectroscopes, reflective rainbow stickers, CD surfaces

E. Cool Applications! ØThin Films - Bubbles & Oil Slicks w interference results from double reflection

E. Cool Applications! ØBlue Sky & Red Sunsets • Molecules in atmosphere scatter light rays. • Shorter wavelengths (blue, violet) are scattered more easily. SUNSET • more atmosphere • more scattering • orange-red sky & sun NOON • less atmosphere • less scattering • blue sky, yellow sun