Unit+9+-+Waves+and+Sound

=Unit 9 - Waves and Sound=
 * **Vibration**- The change in motion of a fluid or an elastic solid whose equilibrium has been disturbed or of an electromagnetic wave, like touching water or swimming, even a heart monitor.
 * **Wave**- In physics, a wave is a change in motion that travels through spacetime, accompanied by a transfer of energy.
 * **Medium** - An intervening substance through which something else is transmitted or carried on. (air, water, solid substances, etc) [[image:punahouphysics/wavelength.gif width="270" height="162" align="right"]]
 * **Wavelength** - Light waves or infrared (heat) waves make patterns as they travel through space. Each wave has a certain shape and length. The distance between peaks (high points) is called wavelength.
 * **Wave Speed** - The speed at which the wave form of a progressive wave travels (equation: speed = distance/time or speed = wavelength x frequency
 * **Displacement**– magnitude and direction of a point on a wave from its equilibrium point
 * **Amplitude**- magnitude and direction of a point on a wave from its equilibrium point
 * **Period**– The length of time it takes for a wave to completely pass.
 * **Frequency**– Frequency is the number of waves per unit of time.
 * **Hertz (Hz)**– The unit for frequency, equal to one cycle per second
 * **Transverse Wave** -A wave that moves back and forth (oscillates) perpendicularly to the axis that the wave travels on. An example would be electromagnetic waves. Waves in water are transverse because the water molecules oscillate up and down perpendicular to the direction of the wave's motion.
 * **Longitudinal wave**- Also known as "I waves" are waves that have their vibration and directions travel in the same direction.
 * **Compression**- A decrease in volume of any object or substance resulting from applied stress. Compression my be undergone by solids, liquids, and gases and by living systems.
 * **Rarefaction**- A decrease in the density and pressure in a medium (Such as air) caused by the passage of a sound wave. (A rarefaction is the place this occurs)
 * **Principle of Superposition** - the net displacement of two waves is the sum of the two individual displacements.
 * **Interference**: Addition (superposition) of 2 or more waves that results in a new wave pattern.
 * **Constructive Interference**: a type of interference that occurs at any location along the medium where the two interfering waves have a displacement in the same direction.
 * **Destructive Interference**: the interference of two waves of equal frequency and opposite phase. This will cause their cancellation where the negative displacement of one always occur during the same time with the positive displacement of the other. [[image:Screen Shot 2012-07-12 at 8.32.15 AM.png width="491" height="281"]]
 * **Total Constructive Interference:** Occurs when waves are in phase with each other. This happens when two of the highest waves are sounded at the same time, allowing them to overlap each other and form an even larger wave than the size of the original separate waves. It only makes sense that when two waves are traveling in the same direction and in the same orientation, a positive interference will take place, rendering only one larger wave instead of the smaller separate waves.
 * **Total Destructive Interference:** Once we have the condition for constructive interference, destructive interference is a straightforward extension. The basic requirement for destructive interference is that the two waves are shifted by half a wavelength. This means that the path difference for the two waves must be: R1 + R2 = l /2.
 * **Node** - points on a wave where there are minimal change in magnitude (red points)
 * **Anti Node** - points on a wave where the change in magnitude is the greatest

==


 * **Natural Frequency-**
 * **Fundamental frequency** - Shortened to “the fundamental”, it the lowest frequency on a sine wave form. A sine wave form is also called a sinusoid and is a wave that keeps its waveform when graphing sine functions. (In english it means that it is the frequency needed to create these constant waves.


 * **Resonance -**
 * **Doppler Effect- A change in the observed frequency of a wave(sound or light) that occurs when the source and observer are in motion relative to each other**
 * **Reflection**: an amount of light, heat, or sound that is thrown back in such a way
 * **Refraction**: bending of light, when light moves from one medium into another; change in the direction of waves as they pass from one medium to another; bending of the path of waves accompanied by a change in speed in wavelength of the waves
 * **Dispersion:** separation of visible light into colors by refraction or diffraction; separation of a complex wave into its component parts according to a given characteristic, such as frequency or wavelength
 * **Diffraction:** apparent bending of waves around small obstacles and the spreading of waves past small opening; change in direction of waves as they pass through an opening or around a barrier in their path
 * **Standing Wave:** wave patterns that are produced on a medium such as a string on a musical instrument

Helpful Websites
http://www.phy.ntnu.edu.tw/ntnujava/index.php?board=3.0 http://www.acs.psu.edu/drussell/demos.html http://lectureonline.cl.msu.edu/~mmp/kap13/cd372.htm http://zonalandeducation.com/mstm/physics/waves/waves.html

Online Practice http://dev.physicslab.org/Document.aspx?doctype=5&filename=WavesSound_SuperpositionPulses.xml http://dev.physicslab.org/Document.aspx?doctype=5&filename=WavesSound_SuperpositionPulses.xml