ch29_jcms


 * //Chapter 29: Reflection and Refraction

29.1: Reflection//**
 * **When a wave reaches the boundary between 2 media, some or all of the waves will reflect back into the original median**
 * **If all of the wave energy is reflected, then it is said to be totally reflected**
 * **If some of it passes into the 2nd median it is said to be partially reflected**


 * 29.2: Reflection**
 * **In two-dimensions, wave reflect off of a boundary at the same angle they arrive, but on a perpendicular imaginary line called the** //normal line//
 * **Angle the wave arrives at is referred to as the** //angle of incidence//
 * **Departing angle is referred to as the** //angle of reflection//
 * **Law of reflection:**
 * **Angle of incidence = angle of reflection**


 * 29.3: Mirrors**
 * **//Virtual images are imaginary and occur behind an object//**
 * **//Virtual images always are the same size and distance behind the mirror as in front//**

//**29.4: Diffuse Reflection**//
 * **Diffuse reflection occurs when a light ray reflects perpendicular to the surface, but reflects off a rough surface and scatters**
 * **The difference between rough and smooth surfaces depends of the wavelength of the wave striking the surface**
 * **If the bumps on the surface are small compared to the wavelength of the wave, than its a smooth surface and vice versa**


 * 29.5: Reflection of Sound**
 * **When sound bounces back off a surface with a noticable delay it is called an** //echo//
 * **If it bounces back and forth in a room it is referred to as** //reverberation//
 * **Sound waves have a much larger wavelength than light waves**


 * 29.6: Refraction**
 * **If a wave strikes a boundary between 2 different media at an angle, than the wave will be bent or refracted as it passes into th 2nd medium.**
 * **This occurs because the speed of thewave changes and the side of the wave that strikes the slower medium first will drag a little an cause the wave to turn in that direction**


 * //29.7: Refraction of Sound//**
 * **Waves do not need a hard boundary between media in order to refract**
 * **They also bend if there is a gradual change in speed**

//**29.8: Refraction of Light**// ni sin Øi = ni sin Ør
 * **When light rays move from a medium where light travels quickly such as air to one where light travels slower like water the light rays will refract toward the normal line.**
 * **If the light rays go in the opposite direction the rays will refract away from the normal line**
 * **Index of Refraction:** index of refraction = speed of light in a vacuum/speed of light in the medium
 * **Snell's Law:**


 * //29.9: Atmospheric Refraction//**
 * **If the air right above the ground is warm but the air above that is cooler then light waves will curve upward**
 * **If you look in the distance this can cause you to see a mirage, when you see waht appears to be a reflecting surface such as water on the ground some distance away**
 * **It will also cause you to see the sun right before it goes down and right before it comes up which results in a five minute longer day**

//**29.10: Dispersion in a Prism**//
 * **Short wavelength light travels through some media at different speeds than longer wavelength light**
 * **The index of refraction varies for different colors of light**
 * **The blue end of the spectrum will refract more than the red end of the spectrum**
 * **This results in seeing a visible spectrum through a prism**


 * //29.11: The Rainbow//**
 * A spectrum is produced when light shines through a raindrops much like it does when it shines through a prism.

//29.12: Total Internal Reflection//
 * When light travels from a dense medium to a less dense medium it will speed up and refract away from the normal line.
 * The angle of incidence that makes the angle of refraction 90 degrees is called the critical angle.