Slide 1

Slide 2

Slide 3

Slide 4

Midpoint (Equilibrium)

Slide 5

Crest (high point) Trough (low point)

Slide 6

Slide 7

Sound is a fascinating phenomenon. When something vibrates in the atmosphere, it moves the air particles around it. Those air particles in turn move the air particles around them, carrying the pulse of the vibration through the air. Ourears pick up these fluctuations in air pressure and translate them into electrical signals the brain can process.Electronic sound equipment works the same basic way. It represents sound as a varying electric current.

Slide 8

Any device that simply produces a better quality and more powerful version of the audio signal.

Slide 9

how often a vibration occurs (# of crests per second) vibrations per second

Slide 10

Heinrich Hertz demonstrated radio waves in 1886. The unit of frequency is the Hertz. 1 vibration per second = 1 Hertz Kilohertz = 1000 v/sec Megahertz = 1000000 v/sec How does a radio work?

Slide 11

Frequency and period are reciprocals of each other. Frequency (f) = 1 period f = 1/T Period (T) = 1 frequency T = 1/f

Slide 12

Sound and light waves move. As waves move, matter is NOT passed along them.

Slide 13

When you create a wave with a rope, it is the disturbance that moves along the rope, not the rope itself.

Slide 14

How fast a wave moves depends on the medium of the wave.

Slide 15

Wave speed is related to the frequency and wavelength of the wave. v = f* Wave speed (m/s) = frequency (Hz) X wavelength (m)

Slide 16

What is the speed of a wave with a frequency of 100 Hz and a wavelength of.025 meters?

Slide 17

v = f Speed = 100 Hz X.025 m Speed = 2.5 m/s How does satellite tv work?

Slide 18

Waves produced when the motion of the medium is at right angles (PERPENDICULAR) to the direction in which the wave travels. EX: Fishing bobber in a lake Fishing bobber in a lake

Slide 19

Waves produced when the particles move ALONG (PARALLEL) the direction of the wave rather than at right angles to it EX: Sound Waves Sound Waves

Slide 20

overlapping waves Interference Patterns Interference Patterns : patterns formed when waves overlap

Slide 21

1. constructive reinforcing interference when waves align at the crests and troughs **individual effects are increased**

Slide 22

2. Destructive cancellation interference Destructive when the crest of one wave aligns with the trough of another **their individual effects are reduced**

Slide 23

Slide 24

Christian Doppler (1803-1853) Change in frequency due to the motion of a sound source

Slide 25

Blue shift = frequency increases as it approaches Red shift = frequency decreases as it leaves

Slide 26

Higher frequency Lower frequency

Slide 27

A slower aircraft sends sound wave crests one at a time and we hear it as a continuous noise.

Slide 28

Chapter 26

Slide 29

Answer: vibrations

Slide 30

All sounds are made by the vibration of material objects.

Slide 31

A vibrating source sends a disturbance through a surrounding medium (such as air) in the form of longitudinal waves.

Slide 32

term that refers to how high or low sound appears to be Is it possible to shatter glass with your voice?

Slide 33

High # of vibrations = high frequency = high pitch EX: piccolo Lower # of vibrations = lower frequency = lower pitch EX: tuba

Slide 34

20 - 20,000 Hz Ultrasonic sound waves above 20,000Hz Infrasonic soundwaves below 20 Hz Humans can hear the range from

Slide 35

When a noise occurs, sound travels in all directions

Slide 36

Any medium that waves travel through; may be solids, liquids or gases Usually, sounds are emitted through air, but they can also pass through solids and liquids

Slide 37

Solids and liquids are generally much better conductors of sound than air EX: ever heard motor boats under water?

Slide 38

Sound travels MUCH slower than light EX: lightening and thunder The speed of sound at room temperature is 340 m/s

Slide 39

Resonance Resonance a phenomenon that occurs when the frequency of forced vibrations on an object matches the objects natural frequency, and a dramatic increase in amplitude results

Slide 40

Resonance can occur in structures EX: marching over bridges swinging bridges by wind

Slide 41

Interference occurs in sound waves. Interference can occur in phase (constructive) or out of phase (destructive) EX: announcer at a football stadium Ripple Tank

Slide 42

Beat periodic variation in the loudness of sound (different frequencies) EX: musical instruments out of tune Musical Beats

Slide 43

What is the beat frequency when a 400 Hz and a 405 Hz tuning fork are sounded together? Answer: Change in frequency = 5 Hz Therefore, the beat frequency is 5 beats per second

Slide 44

Chapter 27

Slide 45

we see objects because light bounces off them Light is energy that is emitted by vibrating electric charges in atoms that travel in waves

Slide 46

Speed of light = extra distance traveled extra time measured = 300,000,000 km / 1000 sec = 300,000 km/sec

Slide 47

light year the distance traveled by light in one year 9.5 x 10 12 km

Slide 48

Waves by which light energy travels All are radiated by vibrating electrons within an atom

Slide 49

Slide 50

Light waves are transverse waves. Polarization the filtering out of all vibrations in a transverse wave, such as a light wave, that are not in a given direction

Slide 51

Reflection bouncing off Refraction penetrating (goes through) and bends