1. 1 Schedule: 1. Do Now 2. Wave Activity 3. Groups present 4. Lecture on Wave Properties 5. Standing wave generator demo **Homework: Conceptual Physics Worksheet 1 Do Now: 1. Come up with at least 3 different kind of waves. 2. Turn to your partner and together think of two more types of waves. Today’s Agenda: Waves Day 2 Objectives: 1. The student will know the units of period, wavelength, frequency, and wave velocity. 2. The student will be able to classify wave types. 3. The student will be able to identify wave characteristics. 4. The student will identify the parts (nodes, antinodes) of a standing wave on a string.

2. 2 Wave Motion Ms. Kinney Adapted from Lori Andersen Wave Properties

3. 3 What is a Wave?  A disturbance that travels from one point to another.  Waves transport energy without transferring matter.  A periodic wave is a regularly repeating series of wave pulses  The direction of propagation is the direction the wave is moving

4. 4 Two Classifications of Waves l Waves can be classified by – Medium through which they are transmitted – Direction of vibration of particles

5. 5 Electromagnetic Waves: waves that do NOT travel through a medium Visible light, X-Rays, Radio Waves, Ultraviolet Rays, Gamma Rays, etc. Mechanical Waves: waves that travel through a medium. Sound, Waves on a string First type of Classification of Waves

6. 6 Two Modes of Wave Travel

7. 7 Characteristics of a transverse wave The dashed line represents the equilibrium position. The points of greatest displacement are called crests (+) and troughs (-).

8. 8 Longitudinal wave The direction of vibration is parallel to the direction of energy transport. Example: Sound Wave

9. 9 Model of a Longitudinal Wave http://www.acs.psu.edu/drussell/Demos/waves/ wavemotion.html

10. 10 Characteristics of a Longitudinal Wave Condensations and Rarefactions in longitudinal waves correspond to crests and troughs in transverse waves.

11. 11 Water Waves How would you describe the motion of the particles? http://www.acs.psu.edu/drussell/Demos/waves/wavemotion.ht ml

12. 12  Sound in air can best be classified using which two of the following terms? (A) Longitudinal (B) Transverse (B) Transverse (C) Electromagnetic (C) Electromagnetic (D) Mechanical (D) Mechanical

13. 13  Sound in air can best be classified using which two of the following terms? (A) Longitudinal (B) Transverse (B) Transverse (C) Electromagnetic (C) Electromagnetic (D) Mechanical (D) Mechanical

14. 14  Light can best be classified using which two of the following terms? (A) Longitudinal (B) Transverse (B) Transverse (C) Electromagnetic (C) Electromagnetic (D) Mechanical (D) Mechanical

15. 15  Light can best be classified using which two of the following terms? (A) Longitudinal (B) Transverse (B) Transverse (C) Electromagnetic (C) Electromagnetic (D) Mechanical (D) Mechanical

16. 16  Crest is to a transverse wave as ________ is to a longitudinal wave. (A) condensation (B) rarefaction (B) rarefaction

17. 17  Crest is to a transverse wave as ________ is to a longitudinal wave. (A) condensation (B) rarefaction (B) rarefaction

18. 18  ___________ is to a transverse wave as rarefaction is to a longitudinal wave. (A) crest (B) trough (B) trough

19. 19  ___________ is to a transverse wave as rarefaction is to a longitudinal wave. (A) crest (B) trough (B) trough

20. 20  Waves transfer ___________ without transferring ___________!

21. 21  Waves transfer _energy__ without transferring _matter___!

22. 22 Wavelength  Symbol - λ (lambda)  Units – any length units  Typical values: Sound Waves: a few meters Sound Waves: a few meters Visible Light Waves: 400-700 nm (1 nm = 10 -9 m) Visible Light Waves: 400-700 nm (1 nm = 10 -9 m)

23. 23 Amplitude  The displacement from the equilibrium position  Units: any units of length  Symbol: A  Indicates how much energy the wave carries Energy is proportional to the square of the amplitude Energy is proportional to the square of the amplitude Sound ~ loudnessSound ~ loudness Light ~ brightnessLight ~ brightness  Wave amplitude is independent of other wave properties

24. 24 Frequency of a Wave  number of complete cycles per second.  Symbol: f  Units: hz 1 hz = 1 s -1 1 hz = 1 s -1  The frequency of a wave is always the same as the frequency of the vibration that created it.  Frequency does not change as waves travel.

25. 25 Frequency of a Wave  Frequency and wavelength are inversely related  Sound waves, frequency determines the pitch we hear.  Light waves, frequency determines the color we see.

26. 26 Period of a Wave  The time for one complete oscillation  Symbol: T  Units: seconds  T = 1/f  If the frequency of the wave is 5 hz, what is the period? T = 1/5 = 0.2 s

27. 27 Wave Speed  Wave speed depends only on the medium the wave travels through. For waves on a string, speed depends on string thickness and tension. For waves on a string, speed depends on string thickness and tension. For sound waves in air, speed depends on air temperature. For sound waves in air, speed depends on air temperature.

28. 28 Wave Speed λEquation: V=f λ –V is wave speed in m/s, f is frequency in hz, and  is wavelength in meters. –Wave Speed is determined solely by the properties of the medium through which the wave travels. –Waves on a String – speed is determined by density of string and tension. –Sound Waves – speed of sound in air is determined by the temperature of the air. –Light Waves – speed of light is determined by the optical density of the material.

29. 29  Homework: Conceptual Physics Worksheet 29