An Introduction to Waves and Wave Properties Waves and Sound An Introduction to Waves and Wave Properties
Announcements Sign in. Take a Packet and a Homework Sheet. Turn in Post-Test from Modern Physics Exam. Homework for this week is Waves and Sound #1
Animation courtesy of Dr. Dan Russell, Kettering University Mechanical Wave A mechanical wave is a disturbance which propagates through a medium with little or no net displacement of the particles of the medium. Water Waves Wave “Pulse” People Wave Animation courtesy of Dr. Dan Russell, Kettering University
Parts of a Wave crest : wavelength 3 equilibrium A: amplitude 2 4 6 x(m) -3 trough y(m)
Speed of a wave The speed of a wave is the distance traveled by a given point on the wave (such as a crest) in a given interval of time. v = d/t d: distance (m) t: time (s) v = ƒ v : speed (m /s) : wavelength (m) ƒ : frequency (s–1, Hz)
Period of a wave T = 1/ƒ T : period (s) ƒ : frequency (s-1, Hz)
Wave Types A transverse wave is a wave in which particles of the medium move in a direction perpendicular to the direction which the wave moves. Example: Waves on a String A longitudinal wave is a wave in which particles of the medium move in a direction parallel to the direction which the wave moves. These are also called compression waves. Example: sound http://einstein.byu.edu/~masong/HTMstuff/WaveTrans.html
Wave types: transverse
Wave types: longitudinal
Longitudinal vs Transverse
Other Wave Types Earthquakes: combination (transverse “s-waves” and longitudinal “p-waves”) Ocean waves: surface (transverse) Light: electromagnetic (transverse)
Reflection of waves Occurs when a wave strikes a medium boundary and “bounces back” into original medium. Completely reflected waves have the same energy and speed as original wave.
Reflection Types Fixed-end reflection: The wave reflects with inverted phase. Open-end reflection: The wave reflects with the same phase Animation courtesy of Dr. Dan Russell, Kettering University
Animation courtesy of Dr. Dan Russell, Kettering University Refraction of waves Transmission of wave from one medium to another. Refracted waves may change speed and wavelength. Refraction is almost always accompanied by some reflection. Refracted waves do not change frequency. Animation courtesy of Dr. Dan Russell, Kettering University
Constructive Interference
Destructive Interference