WAVES 

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

2.  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

3. 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. ?

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

5. 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

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

7. Transverse Wave Characteristics amplitude Crest  Trough 

8. 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/T T = 1/f Wave speed (v)  how fast the wave travels units: Hz(m) = m/s v = f

9. 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? v = f  f = 262 Hz = (262 Hz)(1.28 m)  = 1.28 m v = ? = 335 m/s What would the wavelength of a 128 Hz tuning fork be in the same lab? = (335 m/s) 128 Hz  = v/f = 2.62 m

10. 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? v = f  f = 11waves 60 s = (.183 Hz)(12.0 m) = 2.20 m/s f = .183 Hz  = 2(6.00 m) = 12.0 m

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

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

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

14. Diffraction: Waves spread through an opening--

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

16. 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

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