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What are waves? Def. - Disturbances that carry energy from place to place, through matter or space.

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Presentation on theme: "What are waves? Def. - Disturbances that carry energy from place to place, through matter or space."— Presentation transcript:

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3 What are waves? Def. - Disturbances that carry energy from place to place, through matter or space.

4 Most waves begin with a vibration Waves are made when you speak And heard when you listen Waves can travel through space Waves can make the earth move and shake And make the light you see

5 A medium can be a: is the material in which a wave moves How dolphins communicate wood of a guitar Music from your radio to your ear

6 through medium doesnt move with the wave Energy moves through the medium. The medium just vibrates back and forth and doesnt move with the wave. The medium can move in two ways: 1. Transverse waves 2. Longitudinal waves

7 Medium moves at right angles to the direction of the wave. Ex) football stadium wave A) Crest: highest point B) Trough: lowest point

8 Crest Trough Amplitude Wavelength or Rest position

9 Medium moves parallel to the direction of the wave Ex. – a slinky or metal spring A) Compressions: where the molecules are crowded together B) Rarefactions: where the molecules spread apart. Made up of:

10 CompressionWavelength: Compression + Rarefaction Compression Rarefaction

11 Wavelength Wavelength: the distance between a point on one wave and the identical point on the next. (crest to crest, compression to compression) Unit: Unit: meter Symbol: Symbol: Lambda

12 DefDef: the distance from the crest or trough of a wave to the rest position. Directly related to the amount of energy carried.Directly related to the amount of energy carried.

13 Frequency would be3 Hz Frequency would be 3 Hz If 3 waves went by in 1 second… You have 3 waves per Second Frequency Frequency: the # of waves that pass one place each second. Unit: hertz (Hz)

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15 1.)Type of Medium 2.)Temperature

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17 Waves travel fastest in solids, slowest in gases. Solid Liquid Gas

18 Do molecules move faster or slower as temperature increases? So would sound travel faster or slower as temperature increases?

19 Sound waves travel slower than light waves Speed varies, depending on the medium Air = 340 m/s water= 1440 m/s steel = 5000 m/s

20 V= x f Velocity (m/s) Greek lambda Stands for wavelength (m) Frequency (Hz)

21 A tuning fork has a frequency of 280 Hz and the wavelength of the sound produced is 1.5 meters. Calculate the velocity of the wave. Step 1Step 2Step 3Step 4

22 A wave is moving toward shore with a velocity of 5 m/s. If its frequency is 2.5 Hz, what is its wavelength? Step 1Step 2Step 3Step 4

23 Earthquakes can produce three types of waves. A typical S wave travels 5000m/s. Its wavelength is about 417m. What is the frequency? Step 1Step 2Step 3Step 4

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25 Wave Behaviors Four typesFour types Wave Behaviors Interference ConstructiveDestructive ReflectionRefractionDiffraction 1.Interference3. Refraction 2.Reflection 4. Diffraction

26 Bouncing back of a wave after it strikes a barrier that does not absorb the energy. An echo is a Sound wave that has been reflected Barrier

27 Angle of incidence = angle of reflection

28 Used to locate underwater objects and distances. ***Reflection**

29 Sonograms: Ultrasonic waves (about 20,000 Hz) used to create images of fetuses in the womb Regular sonogram 3D sonogram

30 RefractionRefraction: Bending of waves due to a change in speed (this occurs because the wave changes mediums)

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32 Refraction Why does the pencil appear to be broken when placed in a beaker of water??

33 Diffraction: Bending of waves around the edge of a barrier

34 Def. - Interference is the result of two or more waves passing through a medium at the same time. There are two types of Wave interference: 1. Constructive Interference 2. Destructive Interference

35 biggerConstructive Interference: two crests meet and make a wave with a bigger amplitude.

36 smallerDestructive Interference: one crest & one trough meet and make a wave with a smaller amplitude..

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38 Def.Def. – the study of the science of sound Knowledge of acoustics is important to people who design libraries, concert halls, auditoriums, etc.

39 Longitudinal Wave oscilloscopean oscilloscope is used to convert sound waves into transverse waves, so that we can study them Requires a medium (cannot travel in a vacuum)

40 The highness or lowness of sound. Depends on the frequency of sound waves. High frequency = High pitch Low frequency = Low pitch

41 Human Ear 20Hz Hz Infrasonic: below 20 Hz Ultrasonic Sound: above 20,000Hz nic-ringtones.com/

42 Sonograms: Ultrasonic waves (about 20,000 Hz) used to create images of fetuses in the womb Regular sonogram 3D sonogram

43 Supersonic: faster than the speed of sound. A US Navy F/A-18E/F Super Hornet in Transonic Flight Transonic: where only some parts of the air around an object (such as the ends of rotor blades) reach supersonic speeds (typically somewhere between Mach 0.8 and Mach 1.2).

44 An equal mixture of all frequencies of sound mage:Whitenoisesound.ogg

45 Change in pitch due to motion.

46 *moving towards increases the pitch *moving away decreases the pitch New word for the day: Dopeler Effect (n) The tendency of stupid ideas to seem smarter when they come at you rapidly.

47 Amount of energy measured in decibels (dB) Depends on the amplitude of sound waves. Large Amplitude = Loud sound Small Amplitude = Soft sound

48 Near total silence - 0 dB A whisper - 15 dB Normal conversation - 60 dB Lawnmower - 90 dB Threshold of pain dB A rock concert or a jet engine dB Gunshot, firecracker dB Near total silence - 0 dB A whisper - 15 dB Normal conversation - 60 dB Lawnmower - 90 dB Threshold of pain dB A rock concert or a jet engine dB Gunshot, firecracker dB Measurement of loudness

49 Displeasing sounds that disrupt the activity or happiness of human or animal life. Causes: –Damage to the ear –Stress –Hearing Loss A sound tube designed to decrease roadway noise


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