ch29_esjp


 * Chapter 29 - Reflection and Refraction **

__Sections: __
 * 1) Reflection
 * 2) The Law of Reflection
 * 3) Mirrors
 * 4) Diffuse Reflection
 * 5) Reflection of Sound
 * 6) Refraction
 * 7) Refraction of Sound
 * 8) Refraction of Light
 * 9) Atmospheric Refraction
 * 10) Dispersion in a Prism
 * 11) The Rainbow
 * 12) Total Internal Reflection

**//Chapter 29 Section 1 - Reflection//**

// The picture above represents the difference between the reflection of particles and the reflection of waves. //
 * __reflection-__ the **bouncing back** of a particle or wave that strikes the boundary between two media.
 * <span style="font-family: Georgia, serif;">__totally reflected wave-__ when **all the wave energy is** **reflected back** along the spring rather than being transmitted into the wall.<span style="font-family: Georgia, serif;"> (see figure 29.1 in Conceptual Physics book)
 * <span style="font-family: Georgia, serif;">__partially reflected wave-__ when **part of the wave energy bounces back** along the first spring, while the other part travels along the heavy spring. (see figure 29.2 in Conceptual Physics book)

<span style="font-family: Georgia, serif;">**//Chapter 29 Section 2 - The Law of Reflection//**

//<span style="font-family: Georgia, serif;">The above image shows how the law of reflection works. Such that, the angle of incidence=the angle of reflection. //
 * <span style="font-family: Georgia, serif;">__normal-__ a line perpendicular to a surface.
 * <span style="font-family: Georgia, serif;">__angle of incidence -__ angle between an incident ray and the normal to a surface.
 * <span style="font-family: Georgia, serif;">__angle of reflection-__ angle between a reflected ray the normal to a surface.
 * <span style="font-family: Georgia, serif;">__law of reflection-__ the angle of incidence for a wave that strikes a surface is equal to the angle of reflection. This is true for both partially and totally reflected waves.
 * **angle of incidece = angle of reflection**


 * //<span style="font-family: Georgia, serif;">Chapter 29 Section 3 - <span style="font-family: Georgia, serif;">Mirrors //**

<span style="font-family: Georgia, serif;">~ On a mirror rays of light are reflected from the mirror surface in all directions. ~ The **number of rays is infinite**, and every one obeys the law of reflection. <span style="font-family: Georgia, serif;">//As described below the figures, these two images represent how light rays are affected when in context with a convex and concave mirror.// //<span style="font-family: Georgia, serif;">The above image shows how a virtual image works. //
 * <span style="font-family: Georgia, serif;">__virtual image-__ an image **formed through reflection or refraction** that can be seen by an observer but cannot be projected on a screen because **light from the object does not actually come to a focus**.

<span style="font-family: Georgia, serif;">//**Chapter 29 Section 4 - Diffuse Reflection**//

<span style="font-family: Georgia, serif;">~Reflection of each single ray obeys the law of reflection, the many different angles that incident light rays encounter cause reflection in many directions. ~We see **most** of the things around us by diffuse reflection. <span style="font-family: Georgia, serif;">//In the above image, light rays are hitting a rough surface and scattering in different directions. This represents diffuse reflection.//
 * <span style="font-family: Georgia, serif;">__diffuse reflection-__ the reflection of waves in many directions from a **rough** surface.


 * //<span style="font-family: Georgia, serif;">Chapter 29 Section 5 - Reflection of Sound //**

<span style="font-family: Georgia, serif;">~An echo is reflected sound. ~Sound reflects from all surfaces of a room, such as: walls, ceiling, floor, furniture, and people.
 * acoustics-the study of the need to understand the reflective properties of surfaces.
 * <span style="font-family: Georgia, serif;">__reverberations-__ persistence of a sound, as in an echo, due to **multiple** reflections.

//<span style="font-family: Georgia, serif;">The above figures, though already described underneath the pictures, represents reverberation in a room. //

<span style="font-family: Georgia, serif;"> //<span style="font-family: Georgia, serif;">Pictured above is the Davies Symphony Hall in San Francisco. Above the orchestra are shiny plates that reflect both light and sound. //


 * <span style="font-family: Georgia, serif;">//Chapter 29 Section 6 - Refraction// **

//<span style="font-family: Georgia, serif;">The above picture is a simple representation of how a refracted ray is refracted when hitting a different medium. //
 * __<span style="font-family: Georgia, serif;">refraction- __ <span style="font-family: Georgia, serif;">the **change in direction** of a wave as it **crosses the boundary** between two media in which the wave travels at **different speeds**.
 * <span style="font-family: Georgia, serif;">__wave fronts-__ the crest, trough, or any continuous portion of a two-dimensional or three-dimensional wave in which the vibrations are all the same way at the same time.


 * <span style="font-family: Georgia, serif;">//Chapter 29 Section 7 - Refraction of Sound// **

<span style="font-family: Georgia, serif;">~On a **warm day**, the air near the ground may be appreciably warmer than the air above. ~Since **sound travels faster in warmer air**, the speed of sound near the ground is increased. ~Sound waves will then bend away warm ground, making it appear that the sound does not carry well.

~On a **cold day** **or night**, when the layer of air near the ground is colder than the air above, the **speed of sound near the ground is reduced**. ~The higher speed of the wave fronts above cause a bending of the sound toward the earth. ~When this happens, sound can be heard over considerably longer distances. //<span style="font-family: Georgia, serif;">The above and below images show the way warm and cool air affect how sound travels. //


 * // Chapter 29 Section 8 - Refraction of Light //**

~A pond or swimming pool both appear shallower than they actually are. ~A pencil in a glass of water appears bent. ~Wonder why? ~These effects are caused by changes in the speed of light as it passes from one medium to another, or through varying temperatures and densities of the same medium. //<span style="font-family: Georgia, serif;">This image shows what happens when a person sees a fish swimming in water. As you can see, the image shows how light from the sun and light from the fish are perceived differently to the eye. //


 * <span style="font-family: Georgia, serif;">//Chapter 29 Section 9 - Atmospheric Refraction// **

<span style="font-family: Georgia, serif;">~When atmospheric refraction occurs, there is a speeding up of the wave nearest to the ground and produces a **gradual** bending of the light rays. //<span style="font-family: Georgia, serif;"> These two pictures show the different ways the waves can be reflected. // <span style="font-family: Georgia, serif;"> //<span style="font-family: Georgia, serif;">The above picture shows a representation of a mirage, or how it would be perceived. // <span style="font-family: Georgia, serif;">
 * <span style="font-family: Georgia, serif;">__mirage-__ a floating image that appears in the distance and is due to the refraction of light in the earth's atmosphere.


 * //Chapter 29 Secion 10 - Dispersion in a Prism//**

<span style="font-family: Georgia, serif;"> <span style="font-family: Georgia, serif;">//This picture represents a simple dispersion through the a prism.//
 * <span style="font-family: Georgia, serif;">__dispersion-__ the separation of light into colors **arranged according to their frequency**, by interaction with a prism or diffraction grating, for example.
 * <span style="font-family: Georgia, serif;">dispersion is what enabled Isaac Newton to produce a spectrum!


 * <span style="font-family: Georgia, serif;">//Chapter 29 Section 11 - The Rainbow// **

<span style="font-family: Georgia, serif;">~The conditions for seeing a rainbow are that the sun be shining in one part of the sky and that water droplets in a cloud or in falling rain be in the **opposite** part of the sky. ~When you turn your back to the sun, you see the spectrum of colors in a bow.

//<span style="font-family: Georgia, serif;"> The above image is the rainbow one would see if the ground weren't in the way! This image may also be seen from an airplane, but not very often. //

//<span style="font-family: Georgia, serif;">This is an image of a single raindrop, showing how the light from the sun refracts into the drop then reflects producing the colors of the rainbow! // <span style="font-family: Georgia, serif;">~In a single raindrop, at the first refraction, the light is dispersed into its spectral colors. Violet is bent the most and red the least. ~The rays reach the opposite part of the drop to be partly refracted out into the air and partly reflected back into the water. ~The second refraction is similar to that of a prism, where refraction at the second surface increases the dispersion already produced at the first surface. ~Then, finally, each drop disperses a full spectrum of colors!


 * <span style="font-family: Georgia, serif;">//Chapter 29 Section 12 - Total Internal Reflection// **

<span style="font-family: Georgia, serif;"> <span style="font-family: Georgia, serif;">//This picture shows how internal reflection works, within an optical fiber. As you can see by the arrows, the internal reflection isn't difficult to understand!// <span style="font-family: Georgia, serif;">
 * <span style="font-family: Georgia, serif;">__critical angle -__ the **minimum angle** of incidence for which a light ray is totally reflected within a medium.
 * <span style="font-family: Georgia, serif;">__total internal reflection-__ the 100% reflection (with no transmission) of light that **strikes** the boundary between two media at an angle greater than the critical angle.
 * <span style="font-family: Georgia, serif;">__optical fibers-__ transparent fibers, usually of glass or plastic, that can **transmit** light down its length by means of total internal reflection.
 * <span style="font-family: Georgia, serif;">they are also called light pipes

//**Practice Problems**//

<span style="font-family: Georgia,serif;">The following practice problems were assigned by Mr. Strong and are found in the textbook:

<span style="font-family: Georgia, serif;">Pages 460-461 Review Questions #1, 3, 4, 5, 6, 8, 9, 11, 12, 15, 16, 17, 23, 24, 26 Pages 461-462 Think and Explain #1, 2, 5, 6, 8, 9, 10 Page 462 Think and Solve # 1, 2, 3 //<span style="font-family: Georgia, serif;">
 * Sources** //


 * <span style="font-family: Georgia,serif;">Conceptual Physics: Third Edition with Expanded Technology by Paul G. Hewitt
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