1. Characteristics of Waves
Chapter 15

2. What are Waves? 15.1 Mechanical Waves – 2 Types of Mechanical Waves
Requires matter (medium) to carry energy
Mediums can be gases, liquids, or solids.
produced when a source of energy causes a medium to vibrate
Ex: sound wave, water wave
2 Types of Mechanical Waves
Transverse – move perpendicular (water)
Longitudinal – move parallel (Sound)

3. Waves and Energy
Waves travel through water, but they do not carry the water with them.
WAVE TYPE
WAVE MOVEMENT
mechanical – requires matter to travel
Ex. sound
1. transverse- move at right angles
Ex. light
electromagnetic- does not require a medium to travel
Longitudinal- moves parrallel

4. - Wave Action
Most waves form when winds blowing across the water’s surface transmit their energy to the water.

5. Waves that move the medium at right angles to the direction in which the waves travel are called transverse waves.

6. Longitudinal waves move the medium parallel to the direction in which the waves travel.

7. - What Are Waves?
Longitudinal Waves
The compressions of a longitudinal wave correspond to the crest of a transverse wave. The troughs correspond to rarefactions.

8. Properties of Waves 15.2 4 Properties of Waves Amplitude Wavelength
Frequency
Speed
The distance the medium rises depends on the amplitude of the wave
The more energy a wave has the greater its amplitude

9. Frequency Speed A wave that occurs every second has 1 Hz
Speed = Wavelength x Frequency
Frequency = Speed Wavelength = Speed
Wavelength Frequency
If a medium does not change the speed of the wave is constant
If you increase the frequency of a wave, the wavelength decreases

10. Amplitude, Wavelength, and Frequency

11. Calculating Frequency
- Properties of Waves
Calculating Frequency
Practice Problem
A wave has a wavelength of 2 mm and a frequency of 3 Hz. At what speed does the wave travel?
(2 mm)(3 Hz) = 6 mm/s

12. Calculating Frequency
- Properties of Waves
The speed of a wave on a guitar string is 142 m/s and the frequency is 110 Hz. What is the wavelength of the wave?
Calculating Frequency
(142 m/s)/(110 Hz) = 1.3 m

13. Interactions of Waves 15.3 4 Interactions of Waves Reflection
Refraction
Diffraction
Interference
Constructive Interference
Destructive Interference

14. Reflection
All waves obey the law of reflection

15. Refraction
When a wave enters a new medium at an angle, one side of the wave changes speed before the other side, causing the wave to bend.
Bending only occurs when the wave enters the new medium at an angle, causing one side of the wave to enter the medium first

16. Diffraction
When a wave moves around a barrier or through an opening in a barrier, it bends and spreads out.

17. constructive interference
An adding of energies
Amplitude increases when they meet

18. destructive interference
Subtracting of energies
The part of the wave that has the greatest amplitude wins

19. Standing Waves Standing Waves Nodes Caused by destructive interference
zero amplitude
Caused by destructive interference
Antinodes
Maximum amplitude
Caused by constructive interference

20. Seismic Waves 15.4 3 Types of Seismic Waves P Waves S Waves P waves
Surface Waves
P Waves
Longitudinal
Move faster than other seismic waves
S Waves
Transverse
Cannot travel through liquid
Cause most severe ground movement

22. Earthquakes that occur underwater, like the one off the coast of Chile in 1960, can produce huge surface waves on the ocean called tsunamis.

23. Graphic Organizer Waves Transverse Longitudinal Crests Troughs
can be
can be
Transverse
Longitudinal
contain
contain
contain
contain
Crests
Troughs
Compressions
Rarefactions

24. Chapter Quiz