2. WAVES   A method of energy transfer without the mass movement of particles.  Disturbances that travel through a medium or space Animations courtesy of Dr. Dan Russell, Kettering University

3.  Energy is transferred without the physical net transfer of matter. There are two types of waves: 1) Mechanical Wave-- requires a material medium to travel through SOUND

4. 2) Electromagnetic Waves-- May travel through space (a vacuum) light, X-Rays, gamma rays Mechanical waves are categorized by how they travel through the medium:  Transverse Waves  the displacement of the particles of the medium is perpendicular to the propagation of the wave. ?

5. Breakers are waves that have “fallen over” because the medium is too shallow!

6. Water waves (not breakers) are examples of transverse mechanical waves.  Longitudinal Waves  displacement of the particles of the medium is parallel to the propagation of the wave. Ex: Sound wave

7. Longitudinal Wave Characteristics Compression Rarefaction Wavelength ( )  the distance from one point in phase to the next point in phase. The length of one complete cycle. 2 Reubens tube demo

8. Transverse Wave Characteristics Crest Trough amplitude

9. Period (T)  the time it takes to complete a single cycle- the time for one single wavelength. frequency (f)  the number of cycles per second measured in Hertz (Hz): cycles per second or waves per second f = 1/TT = 1/f Wave speed (v)  how fast the wave travels v = f  units: Hz(m) = m/s

10. A tuning fork that is marked 262 Hz is struck and produces wavelengths that are measured in a lab to be 1.28 m. What is the speed of sound in this lab? f = 262 Hz = 1.28 m v = ? v = f = (262 Hz)(1.28 m) = 335 m/s What would the wavelength of a 128 Hz tuning fork be in the same lab? = v/f = (335 m/s) 128 Hz = 2.62 m

11. Two fishing boats are positioned so that one is atop a crest while the other is at the bottom of an adjacent trough. The boats oscillate and pass each other 22 times in a minute. The boats are exactly 6.00 m apart when they pass each other. What is the speed of the waves that are oscillating the boats? f = 11waves 60 s f =.183 Hz = 2(6.00 m) = 12.0 m v = f = (.183 Hz)(12.0 m) = 2.20 m/s

12. Wave Interactions Light travels in a straight line, very un-wave like: Move one of the boards and…

13. Reflection Bouncing of a wave off of a boundary: Hard Boundary Soft Boundary

14. Refraction: Bending of waves as they change speed passing from one medium to another:

15. Diffraction: Waves spread through an opening--

16. Interference: When waves interact in such a way as to reinforce/cancel each others’ effects:

17. Superposition: the effects of waves on the medium they travel through: Superposition Examples Impedance: the resistance of the medium to passing the wave energy: Impedance Examples Damping: Loss of wave energy traveling through a medium

18. Wave Interactions Rectilinear Propagation Reflection Diffraction Refraction Interference Impedance Damping loss of energy bouncing spreading bending straight line effects of waves wave “friction” Superposition waves affect medium