1. Chapter 11
Waves

2. Waves
wave – a rhythmic disturbance or movement that transfers energy through matter or space
examples:
ocean waves disturb the water and transfer energy through it
light waves travel through empty space to transfer energy from one place to another

3. Waves

4. Waves
wave – a rhythmic disturbance or movement that transfers energy through matter or space
examples:
ocean waves disturb the water and transfer energy through it
light waves travel through empty space to transfer energy from one place to another
waves will exist only as long as it has energy to carry
all waves are created by vibrations

5. Waves
medium – any material through which an energy wave is transferred
the medium for sounds waves is air
the medium for ocean waves is water

6. Waves Mechanical Waves – waves that can only travel through matter
Types of Mechanical waves
transverse wave - a type of wave where the matter in the medium moves back and forth at right angles to the direction that the wave travels

7. Waves
Transverse Waves

8. Waves Mechanical Waves – waves that can only travel through matter
Types of Mechanical waves
transverse wave - a type of wave where the matter in the medium moves back and forth at right angles to the direction that the wave travels
these waves have crests (highest point) and troughs (lowest points)

9. Waves
Transverse Waves

10. Waves Types of Mechanical waves
compressional wave - a type of wave where the matter in the medium moves back and forth in the same direction that the wave travels
similar in movement to the compression and expansion of a spring

11. Waves
compressional wave - a type of wave where the matter in the medium moves back and forth in the same direction that the wave travels
similar in movement to the compression and expansion of a spring
example: sound waves occur when air molecules are pushed together when a surface is hit and that sound is carried through compressions and expansions of the wave through air
causes the eardrum to vibrate when it reaches the eardrum

12. Waves
Compressional Wave

13. Waves Parts of a Transverse Wave
crest – the highest points of the wave
trough – the lowest points of the wave

14. Waves Parts of a Compressional Wave
compression – the denser (or more compressed) region of the wave
example: where the coils are close together
rarefaction – less dense (or more stretched) region of the wave
example: where the coils are more spread out

15. Waves
Compressional Wave

16. Waves Common Parts of Waves
wavelength – distance between one point on a wave and the nearest point just like it
measured in meters (m)
represented with the Greek letter lambda λ

17. Waves Common Parts of Waves
frequency (f) – the number of wavelengths that pass a fixed point each second
measured in hertz (Hz = 1/s)

18. Waves Wave Velocity (v) – describes how fast a wave is traveling
measured in meters per second (m/s)
example: v = 300,000,000 m/s for most electromagnetic waves in a vacuum

19. Waves Calculating Velocities of Waves
the speed of a wave depends on the medium through which it is traveling
sound waves usually travel faster in liquids and solids than they do in gases
light waves and other electromagnetic waves usually travel faster in gases or a vacuum than they do in solids and liquids

20. v =   f Waves Formula for calculating the velocity of a wave:
v: velocity (in m/s)
: wavelength (in m)
f: frequency (in Hz or 1/s)
v =   f

21. Waves
What is the speed of a wave with a wavelength of 2 m and a frequency of 3 Hz?
v =   f

22. Waves
A wave is traveling at a velocity of 12 m/s and its wavelength is 3 m. Calculate the wave frequency.
v =   f

23. Waves amplitude – a measure of the energy carried by a wave
Transverse Waves
the taller the wave, the more energy it has
the shorter the wave, the less energy it has

24. Waves amplitude – a measure of the energy carried by a wave
Compressional Waves
the more dense the wave, the more energy it has
the less dense the wave, the less energy it has

25. Waves
Compressional Waves