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4.5.1 Describe the reflection and transmission of one-dimensional waves at a boundary between 2 media; • When a wave pulse strikes an interface between two different media, some energy rebounds into the original medium and some energy passes into the second medium;
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4.5.1Describe the reflection and transmission of one-dimensional waves at a boundary between 2 media; • When a wave pulse strikes an interface between two different media, some energy rebounds into the original medium and some energy passes into the second medium; • If interface is fixed (immobile), reflected pulse is inverted to the original orientation and most energy is reflected; Reflection - fixed end http://www2.biglobe.ne.jp/~norimari/science/JavaEd/e-wave5.html
Transmission/Reflection http://www.hazelwood.k12.mo.us/~grichert/sciweb/waves.htm • When a wave pulse strikes a barrier, most energy rebounds into the original medium and is inverted... some small amount of energy may pass into the barrier; The Law of Specular Reflection - When a ray of light strikes a smooth, shiny (specular) surface, the angle the ray is reflected, measured from a normal drawn at the point of contact, is equal to the angle of incidence, measured from the same normal. Specular vs. Diffuse Reflection <http://www.glenbrook.k12.il.us/gbssci/phys/class/refln/u13l1d.html>
4.5.2A Describe and Explain Refraction Refraction http://www.sciencejoywagon.com/physicszone/lesson/otherpub/wfendt/huygens.htm 1. A periodic (water) wave approaches a “barrier” (interface) between 2 different media (ie., deep and shallow water); 2. As each HP on wavefront crosses barrier, a new wave front is generated; 3. New wavefront travels slower in shallow water, wavelength decreases; 4. Original wavefront moves a-->b faster than new wavefront moves to c; 5. Direction, speed, and wavelength of wave front have changed...this is refraction;
Optical Density (OD); • OD - the physical property that determines the speed light can maintain as it travels through a transparent material; • OD = Index of Refraction... symbol - n ; Mathematically... n = sin i / sin r...where, i = angle of incidence, and r = angle of refraction • As light leaves the material, it’s speed increases back to c. Thus, the speed of light through a diamond would only be 1.24 x 108 ms-1!! c vmedium n=
Some common indices of refraction: vacuum, n = 1.00 air, n = 1.0003 water, n = 1.33 ethanol, n = 1.36 crown glass 1.52 quartz, n = 1.54 flint glass, n = 1.61 diamond, n = 2.42 More Indices of Refraction http://hypertextbook.com/physics/waves/refraction/ Highest Optical Density? http://physicsweb.org/articles/world/14/9/8
4.5.5 Superposition - Constructive and Destructive Interference •Superposition - the process by which wave amplitudes add together, algebraically (ie., crests [or compressions] act as positive amplitude and troughs [or rarefactions] act as negative amplitude); • When crests add together, the amplitude of the resultant wave increases (constructive interference); • When a crest adds with a trough, the amplitude of the resultant wave decreases (destructive interference); • When troughs add, the negative amplitude of the resultant wave increases (constructive interference). 4.5.6 and 4.5.7 Superposition - the resultant of 2 waves (Leave 1 page blank for several diagrams) Constructive Interference http://www2.biglobe.ne.jp/~norimari/science/JavaEd/e-wave2.html Destructive Interference http://www2.biglobe.ne.jp/~norimari/science/JavaEd/e-wave3.html
