Section 16 Waves and Sound .


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16.1 The Nature of Waves. A wave is a voyaging disturbance.A wave conveys vitality from spot to put.. Transverse Waves. Longitudinal Waves. 16.1 The Nature of Waves. Water waves are somewhat transverse and incompletely longitudinal.. 16.2 Periodic Waves. Intermittent waves comprise of cycles or examples that are created again and again by the source.In the figures, each section of the smooth vibr
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Section 16 Waves and Sound You may not understand it, but rather you are encompassed by waves. The "waviness" of a water wave is promptly obvious, from the swells on a lake to sea waves sufficiently extensive to surf. It\'s less clear that sound and light are likewise waves. Part Goal: To take in the fundamental properties of voyaging waves.

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16.1 The Nature of Waves A wave is a voyaging aggravation. A wave conveys vitality from place to put.

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Transverse Waves

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Longitudinal Waves

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16.1 The Nature of Waves Water waves are incompletely transverse and halfway longitudinal.

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16.2 Periodic Waves Periodic waves comprise of cycles or examples that are delivered again and again by the source. In the figures, each section of the smooth vibrates in basic symphonious movement, gave the finish of the smooth is moved in basic consonant movement.

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16.2 Periodic Waves In the drawing, one cycle is shaded in shading. The abundancy An is the most extreme outing of a molecule of the medium from the particles undisturbed position. SI units are meters. The wavelength λ is the flat length of one cycle of the wave. SI units are meters. The period T is the time required for one total cycle. SI units are seconds.

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16.2 Periodic Waves In the drawing, one cycle is shaded in shading. The recurrence f is the number or waves (or cycles) that go by in a given time. The units are cycles every second, called the Hertz (Hz), or s - 1 . Recurrence is the equal of period. the speed of a wave through some medium is:

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16.2 Periodic Waves Example 1 The Wavelengths of Radio Waves AM and FM radio waves are transverse waves comprising of electric and attractive field aggravations going at a speed of 3.00x10 8 m/s (take note of this is the speed of light !) A station communicates AM radio waves whose recurrence is 1230x10 3 Hz and a FM radio wave whose recurrence is 91.9x10 6 Hz. Discover the separation between neighboring peaks in every wave. AM stands for "plentifulness adjusted" FM remains for "recurrence tweaked" Both of these techniques permit sound to be continued long separations.

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16.2 Periodic Waves Example 1 The Wavelengths of Radio Waves AM and FM radio waves are transverse waves comprising of electric and attractive field unsettling influences going at a speed of 3.00x10 8 m/s. A station communicates AM radio waves whose recurrence is 1230x10 3 Hz and a FM radio wave whose recurrence is 91.9x10 6 Hz. Discover the separation between neighboring peaks in every wave.

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16.2 Periodic Waves AM FM AM radio signs are communicate utilizing a lower recurrence than FM: hence the waves have an any longer wavelength than FM. Some time ago, on a lengthy, difficult experience trip through the unlimited fields of Kansas and Nebraska, you\'d need to change to AM to get radio gathering, and you realize that implied nation western… ..or far more atrocious, talk radio!

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16.3 The Speed of a Wave on a String The speed at which the wave moves to the privilege relies on upon how rapidly one molecule of the string is quickened upward because of the net pulling power. strain straight thickness

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The speed of a wave beat QUESTION:

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The speed of a wave beat

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EXAMPLE 20.1 The speed of a wave beat m/L m/L m/L m/L

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Ratio issue The charts underneath show plentifulness as a component of position (that implies position is on the x-pivot and recurrence is not appeared). Accept string 1 and 2 have a similar length. The mass of string 1 is double the mass of string and the string strain in string 1 is 8x the pressure in string 2. An influx of a similar sufficiency and recurrence goes on each of the strings. Utilizing the relationship v = sqrt (F/m/L), and the relationship v = f λ , figure out which of the photos accurately demonstrates the waves.

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Ratio issue The diagrams underneath show abundancy as a component of position (that implies position is on the x-pivot and recurrence is not appeared). Expect string 1 and 2 have a similar length. The mass of string 1 is double the mass of string and the string strain in string 1 is 8x the pressure in string 2. A rush of a similar sufficiency and recurrence goes on each of the strings. Utilizing the relationship v = sqrt (F/m/L), we find that v 1 = 2v 2 and if the recurrence is equivalent in both cases, then λ 1 = 2 λ 2 and An is right.

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16.5 The Nature of Sound Waves LONGITUDINAL SOUND WAVES

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16.5 The Nature of Sound Waves The separation between neighboring buildups is equivalent to the wavelength of the sound wave.

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16.5 The Nature of Sound Waves Individual air atoms are not conveyed alongside the wave.

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16.5 The Nature of Sound Waves THE PRESSURE AMPLITUDE OF A SOUND WAVE Loudness is a trait of a sound that depends principally on the weight adequacy of the wave.

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16.6 The Speed of Sound goes through gasses, fluids, and solids at extensively extraordinary paces.

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16.6 The Speed of Sound In a gas, it is just when atoms impact that the buildups and rarefactions of a sound wave can move from place to put. These impacts are demonstrated as an adiabatic procedure For a perfect gas, the speed of sound is" k = Boltzmann\'s steady T is the temperature in Kelvin (T c + 273) γ (gamma) is the proportion of particular warmth limits at consistent weight to that of consistent volume C p/C v γ = 5/3 for a perfect monatomic gas γ = 7/5 for a perfect diatomic gas "Air" is displayed as a perfect diatomic gas m is the mass of a particle of the gas in kg

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Speed of sound Carbon monoxide (CO), Hydrogen gas (H 2 ) and nitrogen (N 2 ) are all diatomic gasses that carry on as perfect. In which gas does sound venture to every part of the slowest at a given temperature? A. CO B. H 2 C. N 2

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Speed of sound Carbon monoxide (CO), Hydrogen gas (H 2 ) and nitrogen (N 2 ) are all diatomic gasses that carry on as perfect. In which gas does sound venture to every part of the quickest at a given temperature? A. CO B. H 2 C. N 2 Answer: B, since hydrogen gas has the littlest mass

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16.7 Sound Intensity Sound waves convey vitality that can be utilized to do work. The measure of vitality transported every second is known as the force of the wave. The sound force is characterized as the ability to region proportion. It is connected ( yet not the same as!) to the tumult of the sound. Review the power is the vitality every second discharged by the source The vitality discharged by the source, and hence the power, are the same, paying little respect to the separation of the audience. The force is corresponding to the backwards square of the separation

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If the source discharges sound consistently every which way, the power relies on upon the separation from the source basically. force of sound source territory of circle

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Was it as bravo? Expect that the sound spreads out consistently and any ground reflections can be overlooked. Audience 2 is twice as a long way from the blast as Listener 1. In the event that L1 hears with a force of 1 W/m 2 , with what power does L 2 listen? a. 2 b. ½ c. 4 d. ¼ (units of W/m 2 )

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Fireworks I 2/I 1 = (P/4 π r 2 ) = r 1/r 2 . I 2 is ¼ of I 1 (P/4 π r 1 2 )

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Decibels – a measure of uproar Human listening to traverses a to a great degree extensive variety of forces limit of hearing at ≈ 1 × 10 −12 W/m 2 edge of torment at ≈ 10 W/m 2 . To cover the range, we utilize a logarithmic scale. Sorry about that. It is coherent to put the zero of this scale at the edge of hearing. We characterize the sound power level, communicated in decibels (dB), as: where I 0 = 1 × 10 −12 W/m 2 .

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16.8 Decibels

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16.8 Decibels Example 9 Comparing Sound Intensities Audio framework 1 delivers a sound force level of 90.0 dB, and framework 2 creates a power level of 93.0 dB. Decide the proportion of powers.

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16.8 Decibels β 1 = 93 dB, β 2 = 90 dB, Find I 2/I 1 Divide both sides by 10 dB Take the antilog of both sides Although I 2 is twice that of I 1 , it is not twice as boisterous. Trial information demonstrate that it takes a 10 dB distinction for a sound to be seen as "twice as noisy".

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16.9 The Doppler Effect The Doppler impact is the adjustment in recurrence or pitch of the sound identified by an onlooker in light of the fact that the sound source and the spectator have diverse speeds concerning the medium of sound engendering.

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16.9 The Doppler Effect MOVING SOURCE

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16.9 The Doppler Effect source moving toward a stationary onlooker source moving far from a stationary eyewitness

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16.9 The Doppler Effect Example 10 The Sound of a Passing Train A fast prepare is going at a speed of 44.7 m/s when the designer sounds the 415-Hz cautioning horn. The speed of sound is 343 m/s. What are the recurrence and wavelength of the sound, as seen by a man remaining at the intersection, when the prepare is (a) drawing nearer and (b) leaving the intersection?

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16.9 The Doppler Effect moving toward leaving

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16.9 The Doppler Effect MOVING OBSERVER

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16.9 The Doppler Effect Observer moving towards stationary source Observer moving far from stationary source

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16.9 The Doppler Effect GENERAL CASE Numerator: in addition to sign applies when onlooker moves towards the source Denominator: short sign applies when source moves towards the eyewitness

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16.10 Applications of Sound in Medicine By filtering ultrasonic waves over the body and distinguishing the echoes from different areas, it is conceivable to get a picture.

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16.10 Applications of Sound in Medicine Ultrasonic sound waves cause the tip of the test to vibrate at 23 kHz and smash segments of the tumor that it tou

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