Sound+and+Light

__ Chapter 15: Sound and Light __

__Properties of Sound__ A Sound Wave is a longitudinal wave that is caused by vibrations andthat travels through a material medium. Sound Waves are caused by vibrations,and carry energy through a medium. Sound waves in air spread out in all directions away from the source. The speed of sound depends on the medium. The speed of sound in air at room temp.is about 346m/s (760 mi/h). Sound travels faster through liquids and solids than through gases. Particles in solids and liquids are closer together than in a gas, so the vibrations are transferred more rapidly. Relative Intensity of soundsis found by comparing the intensity of a sound with the intensity of the quietest sound a person can hear. Intensity is measured in Decibels. Pitch is a measure of how high or low a sound is perceived to be depending on the frequency of the sound wave. Pitch is measured by frequency. Infrasound is slow vibrations of frequencies lower than 20 Hz (hertz). Ultrasound is any sound wave with frequencies higher than 20,000 Hz (hertz). === ===

The above picture shows the formula for how to find the speed of sound. __Musical Instruments__

Musical Instruments rely on standing waves. Vibrations on a guitar string produce standing waves on the string. These standing waves in turn produce sound waves in the air. The frequency of standing waves is called the fundamental frequency. Harmonics give every instrument a unique sound. Harmonics are an instruments fundamental frequency and at certain whole-number multiples of that frequency. Resonance is a phenomenon that occurs when two objects naturally vibrate at the same frequency. Instruments use resonance to amplify sound. __Hearing and the Ear__ Your ear is divided into three regions, outer, middle, inner. Sound waves strike the eardrum, which causes the eardrum to vibrate. The vibrations then pass from the eardrum to the three small bones of the middle ear. When the vibrations reach the stirrup, the stirrup strikes a membrane opening of the inner ear. Resonance occurs in the inner ear.

__Ultrasound and Sonar__

Sonar is **S**ound **N**avigation **A**nd **R**anging, a system that uses acoustic signals and echo returns to determine the location of objects or to communicate. Sonar is used for underwater location. Ultrasound imaging is used in medicine. Ultrasound is used to produce computerized images called sonograms which are used to see organs and view unborn babies. Some ultrasound waves are reflected at boundaries. Ultrasound waves can pass through most materials but some sound waves are reflected when they pass from one type of material into another.

= Chapter 15: Reflection and Color = Every object reflects some light and absorbs some light. Because mirrors reflect light, it is possible for you to see an image of yourself in a mirror

The angle of the light rays reflecting off the surface, called the angle of reflection, is the same as the angle of the light rays striking the surface, called the angle of incidence. This is called the law of reflection. The angle of incidence equals the angle of reflection This picture shows that when white light reflects off of an object of a different color that color is reflected back. Into your eyes. With the exception of black.

[]://www.daviddarling.info/childrens_encyclopedia/light_Chapter6.html&usg=ftntKpU_OI5ZaBVXSJy0tuwf5gw=&h=542&w=300&sz=58&hl=en&start=0&sig2=uRqyBRykSMb1eZXI11HbBQ&zoom=1&tbnid=3LTAdApAK4o8CM:&tbnh=121&tbnw=67&ei=unnmTY-kCYjVgQelqKW4Cg&prev=/search%3Fq%3Dcolor%2Band%2Breflection%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26biw%3D1280%26bih%3D574%26tbm%3Disch&um=1&itbs=1&iact=rc&dur=97&page=1&ndsp=22&ved=1t:429,r:1,s:0&tx=55&ty=33&biw=1280&bih=574//

Flat mirrors form virtual images by reflection.When a light ray hits a mirror then is reflected, the angle it is reflected is equal to the angle of incidence (law of reflection). The image that you see in a mirror results from the apparent path of the light rays, not an actual path. This is a virtual image. The virtual image to be as far behind the mirror as you are in front of the mirror.

Concave mirrors can create real images. A concave mirror can form a virtual image and a real image of the mirror. A real image results when light rays from a single point of an object are focused onto a single point or small area. With a real image, light rays really exist at the point where the image appears.

Objects have color because they reflect certain wavelengths. The different wavelengths of visible light correspond to many of the colors you perceive. When you see an object, light reflects off it and enters your eyes, your brain then interprets it as a color. When you see an apple your brain tells you the apple is red. This happens because light reflects off of the apple into your eyes and your brain sees it as a color. This object's particular color being red.

//[]://www.colormatters.com/images3/apple-reflect-eye.jpg&imgrefurl=[]__0OY3H8MFiNEh2fgmIwxKBSrxb04=&h=264&w=420&sz=7&hl=en&start=0&sig2=x99u9yhLIvYhecX2dvninQ&zoom=1&tbnid=eVUydjJOArd62M:&tbnh=106&tbnw=168&ei=unnmTY-kCYjVgQelqKW4Cg&prev=/search%3Fq%3Dcolor%2Band%2Breflection%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26biw%3D1280%26bih%3D574%26tbm%3Disch&um=1&itbs=1&iact=rc&dur=275&page=1&ndsp=22&ved=1t:429,r:2,s:0&tx=70&ty=72&biw=1280&bih=574__

Additive primary colors are red, green, and blue. Subtractive primary colors are yellow, cyan, and magenta. Red, green, and blue lights can combine to produce yellow, magenta, cyan, or white. Yellow, magenta, and cyan filters can be combined to produce red, green, blue, or black.

This photo shows how a rainbow is made by reflection. Light from the sun reflects off particular raindrops into the eyes of the observer. Seeing them as different colors.

__[]:__//wiki.pingry.org/u/physics/images/4/48/Rainbow_physics.jpg&imgrefurl=[]

I found two videos that will help you to understand reflection and color. And to further explain certain things.

[] This one is more informational, giving you a step by step lesson.

[] This video shows a 3D model of how light and color is reflected.

This is a hands-on activity to find the color of light you can do right in the classroom. []