Grade 10 Unit AP.4 Waves and - Science Curriculum Office ...



Physics Grade 10 Advanced Level -581660-327660 ContentsUNIT 4: Waves and Sound-476250154305-890270353695Core Standards……………………………..…….. 3 Objectives…………………………….....…........….. 428.1- Waves and Wave Pulses ….…………..........…….…….. 528.2 Waves ……………..….……......................................….. 828.3 Describing Wave……………………….……...….. 1228.4 Sound waves ………...........................................….. 1828.5 Speed of sound………...…..................................….. 2428.8 Standing waves and travelling waves…..........….. 29-404495149225 Questions………………………………............….. 38-50546037465 References………………………..…………........... 444659289-211540-151547-21154010A.28.1 Distinguish between a wave pulse and a continuous travelling wave, give examples of both and understand what is meant by wave front.10A.28.2 Know that waves transfer energy and distinguish between transverse and longitudinal waves.10A.28.3 Know and use the terms crest, trough, compression, rarefaction, displacement, amplitude, phase difference, period, frequency, wavelength and velocity, and perform calculations using the relationships between velocity, frequency and wavelength.10A.28.4 Know that sound is a longitudinal vibration transmitted through a medium, and that it is created by a vibrating object such as a vibrating string or air column.10A.28.5 Know that the velocity of sound depends on the medium though which it travels, and that it travels faster and more efficiently through media in which the particles are close together.10A.28.8 Distinguish between a standing and a travelling wave, know the meaning of the terms node and antinode, and illustrate the phenomenon of resonance with particular reference to vibrating stretched strings and air columns.-215265-4572004526915-457200By the end of the unit, students know that energy is transferred in the form of pulses and waves, and understand and manipulate the measurable parameters associated with waves. They know that sound is a waveform that requires a medium, they measure its speed in air and know how the ear detects sounds.Students who progress further distinguish between standing and progressive waves, know how harmonics are produced, and describe the phenomenon of resonance with reference to air columns and stretched strings. Waves and Wave Pulses??????? ???? ?????? 28.18261352286004249420265430A wave is an oscillation that travels.A ball floating on water can oscillate up and down in harmonic motion.The surface of the water oscillates in response and the oscillation spreads outward from where it started.?????? ?? ?????? ?????????? ???? ???? ?? ????? ???? ?? ???? ????? ????? ?? ???? ???????? ??? ????? ???? ??? ????? ?????? ???????? ?????? ?? ??????Why we learn about waves?????? ????? ?? ???????4044950249555Waves carry useful information and energy.Waves are all around us:light from the stoplightripples in a puddle ofelectricity flowing in wiresradio and television and cell phone transmissions???? ??????? ????????? ?????? ?????????????? ?? ?? ?? ??????????? ?? ?????? ????????????? ?? ?????????? ???????? ?? ?????????????? ??????? ?????????Characteristics of waves????? ???????Waves have cycles, frequency, and amplitude, just like oscillations.?????? ????? ????? ???? ?????? ??? ??????????The frequency of a wave tells how often each point oscillates.The amplitude of a wave is the maximum movement from equilibrium.The wavelength of a wave is the length of one complete cycle.Wave pulses??? ??????A wave pulse is a short length of wave, often just a single oscillation.??? ?????? ?? ???? ??? ?????? ??????? ?? ???? ??????? ????? 190509144028.2Waves???????754380323850A wave may be defined as a periodic disturbance in a medium that carries energy from one point to another.????? ?????? ????? ?????? ???? ?? ????? ????? ???? ??? ?????? ?? ???? ?????.All waves require a source and a medium of propagation.?? ??????? ????? ????? ???? ????? ????????.??Waves may lose energy as they propagate through a dense medium (attenuation).??? ?????? ?????? ???? ??? ???? ????? ???? ???? Waves that radiate isotropically (uniformly in all directions) from a source also lose intensity due to the fact that the energy they carry is spread out over an increasingly large area. This is known as the inverse square law.??????? ???? ????? ??????? ?? ???? ????????? ?? ?????? ???? ????? ????? ???? ?????? ?????? ???? ?????? ???? ??? ???? ??????? ???? ???? ?????? ??????? ??????.??There are two distinct types of waves: Longitudinal and Transverse. Sound waves are an example of longitudinal waves while electromagnetic waves, such as light, are examples of transverse waves.???? ????? ?????? ??????? : ????? ????????. ????? ????? ?? ???? ??????? ??????? ????? ??????? ??????????????? ??? ????? ?? ???? ??????? ?????????.Transverse and Longitudinal waves??????? ??????? ??????????Transverse and Longitudinal waves can both be categorized under the term Mechanical Waves. Mechanical waves require a substance to travel through whereas electromagnetic waves like light don't.??????? ??????? ?????????? ???? ????? ?? ??????? ??? ??? ??????? ???????????. ???????? ??????????? ?? ???? ????? ???? ???? ???????? ??? ??? ??????? ??????????????? ???? ?? ????? ???? ???? ??? ?????. Examples of transverse and longitudinal waves are things like water waves, sound waves, or waves that travel along a spring or rope. ?? ????? ??????? ??????? ?????????? : ????? ????? ?????? ????? ?????? ??????? ?? ?????.In a transverse wave the particles of the substance or ‘medium’ moves perpendicular to the direction of the motion of the wave. ?? ??????? ????????? ??? ?????? ????? ????? ??????? ??? ????? ?????? ??????. If a little girl push a rope up and down, oscillation at one end of the string creates waves that propagate, or travel, down the length of the string. These are called traveling waves. The wave travels but the string only oscillates up and down. ??? ???? ??? ?????? ??? ????? ???? ???? ?? ??? ???? ????? ??? ?????? ??? ????? ????? ?? ???? ????? ????? ??? ??? ?????. ???? ?? ?????? ????? ??? ??? ????? ???? ????? ???? ???? ??? ?????? ???? ??????.4965065246380See how this snakes body moves like a transverse wave. ???? ??? ?? ??? ??????? ???? ????? ??????? ??? ????? ??? ?????.Longitudinal Waves??????? ???????In a longitudinal wave the substance or ‘medium’ moves parallel to the direction of the motion of the wave. ?? ??????? ??????? ????? ?????? ????? ?? ??? ????? ?????? ??????A longitudinal wave can be created in a slinky. When the slinky is stretched out in a horizontal direction and the first coils of the slinky are vibrated horizontally. ???? ??? ???? ????? ???? ??? ???????. ??? ?? ????? ?????? ?????? ????? ?? ?????? ?????? ?? ????? ???? ??????Each individual coil of the medium is set into vibrational motion in directions parallel to the direction which the energy is transported. ?? ??? ?? ???? ????? ???? ?? ??? ????? ?????? ??????.Longitudinal Waves are referred to as sound waves because the particles that need to travel through the medium which transport the sound are transported by vibrating parallel to the direction which the sound moves. ????? ????? ?? ????? ????? ??? ?????? ????? ???? ?? ??? ????? ?????? ???? ?????.As the vibrating string moves in the forward direction, it begins to push upon surrounding air molecules, moving them to the nearest particle. This causes the air molecules to be compressed into a small region of space. As the vibrating string moves in the reverse direction it lowers the pressure of the air immediately. ????? ???? ???? ????? ?????? ???? ???? ?????? ?????? ??? ???? ?????? ??? ???????? ?? ??? ????. ?????? ???? ????? ???? ????? ?? ??? ?????? ??????. The lower pressure of the string causes air molecules in that region immediately to move to the right of the string to expand into a large region of space. The back and forth vibration of the string causes individual air molecules (or a layer of air molecules) in the region to move back and forth horizontally; the molecules move rightward as the string moves rightward and then leftward as the string moves leftward.???? ???? ????? ?????? ?????? ???? ???? ?????? ?????? ?????? ?????? ????? ??????.43243501357630 These back and forth vibrations are imparted to adjacent neighbors by particle interaction; thus, other surrounding particles begin to move rightward and leftward, thus sending a wave to the right. Since air molecules (the particles of the medium) are moving in a direction which is parallel to the direction which the wave moves, the sound wave is referred to as a longitudinal wave. See Caterpillars move like longitudinal waves! ???? ?? ?????? ????? ?????? ????? ?????? ???????.28.3Describing Waves??? ??????3712845396875There are many ways to describe or measure a wave. Some methods depend on how the wave is produced, whereas others depend on the through which the wave travels.On the right, transverse waves are being sent along a rope. Here are some of the Terms used to describe these and other waves:???? ??? ?????? ??? ???????? ???? ????? ??? ?? ?????? ????? ???? ?????? ?? . ????? ???? ????? ??????? ??????? ???? ??????? ??? ???????.Speed (V)The speed of the waves is measured in meters per second (m/s).Frequency(f) This is the number of waves passing any point per second. The SI Unit of frequency is the hertz (Hz). For example, if the hand on the right makes 4scillations per second, then 4 waves pass any point per second, and the frequency is 4 Hz. ?????? ?? ??? ??????? ?????? ????? ?? ?????. ????? ????? ???????Period (T) The time for one wave. It is equal to 1/frequency. If the frequency is 4 Hz, the period is 1/4 s (0.25 s)????? ?????? ?? ??? ???? ????? . ?????? ????? ??????. ?????? ???????.Amplitude (A) This is the maximum distance a point moves from its rest position when a wave passes.????? ?? ???? ????? ??? ????? ???? ?? ????? ?? ???? ??????.Wavelength (λ) This is the distance between any point on a wave and the equivalent point on the next.944880342900????? ?????? ?? ??????? ??? ?? ???? ?? ?????? ??????? ???? ??????? ?? ?????? ???????. Figure shows Transverse waves, the low points, or troughs, and the high points, or crests, of a wave. The shortest distance between points where the wave pattern repeats itself is called the wavelength. Crests are spaced by one wavelength. Each trough is also one wavelength from the next. The Greek letter lambda, λ, represents wavelength.261620506095????? ???? ????? ??????? ??? ???? ???? ???? ?? ?????? ?????? ????? ???? ?????? . ??? ???????? ??? ????? ????????? ?? ????? ??????? ???? ???? ????? ??????.Figure shows Longitudinal waves, the region in which molecules are closer together is the Compression. the region in which the molecules are further apart is the Rarefaction. Wavelength (λ) is the distance between successive rarefactions or between compressions. ????? ???? ????? ????? ??? ???? ??????? ???? ???? ???? ???????? ???? ?? ???? ?? ????? ????? ???????? .????? ??????? ???? ???? ???? ???????? ??????? ????????. ??? ???????? ??? ??????? ???????? ?? ??????? ???????? ???? ????? ??????.Phase and phase difference????? ???? ?????1148080369570All points along a wave have the same pattern of vibration – they all vibrate up and down, back and forth, or from side to side, or whatever. However, different points do not necessarily vibrate in step with one another. As one point on a stretched string vibrates up and down, the point next to it vibrates slightly out-of step with it. We say that they vibrate out-of-phase with each other - there is a phase difference between them.As you can see from figure two equivalent points on a wave (points A and B)vibrate in phase with each other. The phase difference between any other two points can have any value between 0° and 360°. (A complete cycle of the wave is thought of as 360°.)???? ?????? ?? ?????? ???? ?????? ????? ???? ?????? ???? ???? ???? ??????? ??? ?????? A,B ???? ????? ?? ?????. ???? ????? ?????? ????? ????.??? ?????? C,D????? ?????? ?????? ????? ?????? ?? ?????.??????? ??? ????? ??? ?????? ?? 0 ???360o.Activity???? The ripple tank ??? ??????? -125095-226060-208280213360We can study the behavior of water waves using a ripple tank.When the motor is turned on the wooden bar vibrates creating a series of ripples on the surface of the water. A light placed above the tank creates patterns of the water waves on the floor. By observing the patterns we can see how the water waves are behaving.At low speeds, the motor on the ripple tank produces a small number of waves each second. The frequency of the waves is small and the pattern shows that the waves have a long wavelength. At higher frequencies, the water waves have shorter wavelengths.The speed is constant.-138430353060??? ????? ??? ??????? ???? ????? ??????? ??? ?????? ?????? ?????? ?????? ????? ?????? ??? ?????? ?????? ??? ????? ?????? ?? ???? ?????? ????? ??? ??????? ???? ???? ???? ????? ????? ?? ?????? ??? ????? ??????. ???? ?????? ?? ????? ?????? ?????The wave equation???????? ?????? ???????Speed = frequency x wavelength????? ?????? × ?????? = ???? ??????V = f x λm/s Hz mThe speed, frequency, and wavelength of any set of waves are linked by this equation.815340407670The following example shows why the equation works:The waves on the right are travelling across water.Each wave is 2 m long, so the wavelength is 2 m. One second later...3 waves have passed the flag, so the frequency is 3 Hz.the waves have moved 3 wavelengths (3 x 2 m) to the right so their speed is 6 m/s?? ????? ????? ????? ?? ????? ?????? ????? 2m????? ????? ??? ???? ????? ????? ??? ???? ?? ?????? 3Hz ???? ???? ??? ??????? 6m/s 28.4Sound waves ??????? ???????Making sound waves????? ??????? ??????? SOUND a mechanical wave (longitudinal) that is a range of compression wave frequencies to which the human ear is sensitive. It will not travel through a vacuum.????? ?? ????? ????????? ?????? ??? ?????? ?? ???????? ??????? ????????? ??? ??? ??????? ???? ??? ???. ??? ????? ?? ????? ?? ??????.All sounds are produced by vibrating objects and vibrating columns of air:?? ??????? ???? ?? ?????? ??????? ??? ?????? ????? ??????.Usually the small vibration stimulates vibration of a larger object (the sounding board of an instrument, air in the throat and mouth of someone talking???? ?? ???? ????????? ??????? ??????? ??? ???? (?????? ?????????? ?????? ?? ??????? ?? ????? ?? ???? ????? ????? ?????).This vibrating material sends a disturbance through the surrounding air, that then propagates through surroundings in form of longitudinal waves. You can use a wave machine model and/or a Slinky to demonstrate how a source of vibration gives rise to longitudinal travelling waves.??? ?????? ???? ???? ???? ???????? ?? ???? ?????? ?????? ???? ????? ??? ??? ????? ??? ??? ????? ?????. ????? ??????? ????? ??? ??????? ?? ???? Slinky ????? ??? ?? ???? ???????? ????? ????? ????? ??????.If an object vibrates it causes waves in the air (like when throwing a stone into a lake.) When these waves hit your eardrum, it'll vibrate in the same way as the object, your brain turns this vibration into the sense of sound. 73850571120??? ???? ????? ???? ?????? ????? ?? ?????? (???? ???? ????? ?? ???? ???). ?????? ????? ????? ????? ????? ????? ????? ??? ???? ???? ??????? ? ???? ????? ????? ??? ????????? ??? ????? ??????.The vibrations of air can be amplified when they are passed through a cone shaped speaker such as a megaphone or the bell of a trumpet.???? ????? ???????? ?? ?????? ????? ???? ?? ???? ?????? ??? ?????? ????? ??? ?????? ????? (?????????) ?? ??? ?????.While all sound begins with vibrating things, there are different ways of making things vibrate.?? ??? ?? ???? ??????? ???? ??????? ???????? ??? ???? ????? ?????? ???? ??? ??????? ????.Activity???? 1 Tuning Fork ?????? ??????? 27731-764412787015179705 You will need a tuning fork, cork and beaker of water.??? ????? ??? ???? ?????? ????? ????? ?????.Tap the tuning fork gently on the cork.???? ?????? ??????? ??? ?????? ????.What do you hear? ???? ????? Tap the tuning fork again, then gently touch the prongs.???? ?????? ??????? ??? ????? ?? ?????? ??????? ????.What do you feel? ?? ?? ????? Tap the tuning fork again, then gently put the prongs onto the surface of the water in the beaker.???? ?????? ??????? ??? ????? ?? ?? ??????? ???? ??? ??? ????? ?? ??????. What do you see? ???? ??? ?What is the tuning fork giving to the water? ?? ???? ????? ?????? ??????? ??????17820274030Activity???? 2 Human Voice ??? ??????? 1177925163830 Gently put your fingers on your throat. Speak or sing quietly.What do your fingers feel?What do you think is happening inside your throat?Explain how the sound of your voice travels through the air.Air from your lungs passes over the vibrating vocal chords, making sound???? ??????? ???? ??? ??????. ???? ?? ???? ?????.???? ???? ??????? ?? ???? ?? ?? ???? ???? ??????????? ??? ?? ???? ????? ???? ??????.?????? ???? ?? ??????? ??? ?????? ??????? ??????? ??????? ?????.Activity???? 3 Loudspeakers ?????? ????? -78740-3009902862580204470A loudspeaker gives out sound energy where it vibrates back-and-forth, creating compression waves in the air.Loudspeakers are used in devices such as mobile phones and radios.???????? ????? ???? ???? ????? ??? ???? ?????? ???????? ????? ????? ??????? ?? ??????.?????? ?? ??????? ??? ??????? ???????? ?????? ???????.Think of some other devices which contain loudspeakers.????? ???? ??????? ???? ????? ??? ???????? ?????.1) Your teacher will show you a large loudspeaker. Gently touch the loudspeaker when it is giving out sound energy and some small pieces of paper have been placed on it.??? ???? ?? ??????? ???? ??? ????. ???? ???? ???????? ??? ??? ??? ????? ????? ????? ????? ???????? ?????.What do you see and feel? ???? ??? ?????? 2) Your teacher will give you some apparatus and show you how to make a model loudspeaker.??? ????? ??????? ??? ??????? ?????? ????? ????? ????? ??????? ?????.1025525151130How does a loudspeaker create sound???? ???? ???????? ??????-182880192405Activity???? 3 Musical Instruments ?????? ????????? ReedsStringsAir columns Membranes (Drum, Tambourine)How do you think each of these musical instruments produce sound energy? ??? ???? ??? ?????? ????????? ?????? Speed of sound???? ?????28.54277995130810Speed of sound depends on the medium???? ????? ????? ??? ????? ??????Sound waves can travel through solids, liquids, and gases. Because waves consist of particle vibrations, the speed of a wave depends on how quickly one particle can transfer its motion to another particle. For example, solid particles respond more rapidly to a disturbance than gas particles do because the molecules of a solid are closer together than those of a gas are. ??????? ??????? ???? ?? ????? ?? ???? ?????? ?????? ???????? ????????. ????? ?? ??????? ????? ?? ?????? ?????? ??? ???? ?????? ????? ??? ??? ???? ??? ?????? ?? ???? ??? ???. ?????: ???????? ?? ?????? ?????? ?????? ????? ???? ???????? ???? ?? ?????? ????????? ????? ?? ?????? ?????? ???? ??????? ???? ???? ?? ?????? ???????.As a result, sound waves generally travel fastest in solids and slowest in gases, but there are some exceptions. ??????? ??????? ??????? ???? ??? ????? ???? ?? ?????? ?????? ????? ?? ?????? ????????? ??? ???? ??? ???????????.The speed of sound also depends on the temperature of the medium.???? ????? ????? ????? ??? ???? ????? ????? ??????As temperature rises, the particles of a gas collide more frequently. Thus, in a gas, the disturbance can spread faster at higher temperatures than at lower temperatures. In liquids and solids, the particles are close enough together that the difference due to temperature changes is less noticeable.????? ????? ???? ???????? ???????? ?? ????? ????? ?????? ??????. ???????? ???? ?? ????? ???????? ?? ????? ???? ?? ????? ??????? ???????. ?? ?????? ??????? ???????? ???????? ???? ??????? ???? ????? ??? ???? ??? ???????? ?? ????? ??????? ??? ??????.The table below shows the speed of sound waves in various media.?????? ?????? ????? ???? ??????? ??????? ?? ????? ??????.Speed of Sound in Various MediaMediumv (m/s)Gasesair (0°C)331air (25°C)346air (100°C)366helium (0°C)972hydrogen (0°C)1290oxygen (0°C)317Liquids at 25°Cmethyl alcohol1140sea water1530water1490Solidsaluminum5100copper3560iron5130lead1320vulcanized rubber54Activity???? What Does Sound Travel Through? ?? ???? ???? ????? ?????? -136525-113665Wood is a solid. The tables are made of wood.Put one ear on the table and tap gently on the table.Does sound energy travel through solids like wood?????? ???? ????.???????? ?????? ?? ?????.?? ???? ????? ??? ??????? ????? ???? ??? ???????.?? ?????? ??????? ????? ?? ???? ?????? ?????? ??? ??????Water is a liquid.Think about the last time you had a bath or went swimming.Does sound energy travel through liquids like water?????? ???? ?????.???? ???? ??? ???? ?????? ?? ???? ???????.?? ????? ?????? ??????? ?? ???? ?????? ??????? ??? ??????1075690-2540Air is a gas.Listen to what is going on around you.Does sound energy travel through gases like air??????? ???? ??????.????? ??? ???? ???? ????.?? ????? ?????? ??????? ?? ???? ?????? ???????? ??? ???????Electric bell in a glass bell jar.Your teacher will show you an electric bell in a glass bell jar which is full of air.Can you hear the bell ring?Explain why.Your teacher will now pump the air out of the jar. This creates a vacuum in the jar.What is a vacuum?Can you hear the bell ring now?Explain why?Why do you think that "outer space" is very quiet?????? ?????????.??? ???? ???? ??????? ????? ????????? ???? ???? ????? ????? ???????.?? ???? ?? ???? ???? ?????????? ????????? ?????? ??????? ?????? ?? ?????? ???? ??? ?????? ?????.?? ?? ????????? ???? ?? ???? ???? ????? ????????? ??????????? ????? ?? ?????? ??????? ???? ?????Activity???? Speed of sound in air???? ????? ?? ?????? 13970-173990The students stand to a measured distance (a few tens of meters) from a wall. One student claps hands once and another student listens for the echo, then claps with a regular rhythm such that each new clap coincides exactly with hearing an echo.??? ?????? ??? ????? ??? ????? ?? ??????? ?? ??????. ??? ?????? ???? ??? ????? ????? ??? ????? ?????? ?? ???? ?? ????? ????? ???? ?? ?????? ????? ?????? ?????? ?? ???? ?????.The other students measure the time for several claps. They can then work out the interval between adjacent claps and hence calculate the speed of sound in air.?????? ??????? ?????? ????? ????????? ????????. ??????? ????? ????? ??????? ??? ????????? ????????? ?? ???? ???? ????? ?? ??????.28.8Standing waves and travelling waves ??????? ???????? ???????? ???????? 4803140259715If you hold a seashell up to your ear, you will hear the roar of the waves rolling onto the shore.Why do you think you hear these sound???? ???? ???? ?????? ?? ????? ???? ????? ???? ??????? ??? ??????. ????? ???? ??? ????????Standing waves and travelling waves:The notes we hear from the guitar are created by the vibration of its strings. The wave patterns on the vibrating strings are called standing waves. The waves which carry the sound to our ears transfer energy, and so are called travelling waves.??????? ???????? ???????? ????????:???? ??????? ???? ???? ?? ???????? ???? ?????? ????? ????????. ????? ??????? ???? ????? ?? ??????? ??????? ???? ??????? ????????. ??????? ???? ???? ????? ??? ???? ???? ?????? ???? ???? ??????? ????????. Formation of standing waves???? ??????? ????????900430113665What happen when the hand moves up and down the rope?Waves generate in the rope.???? ???? ??? ????? ????? ??? ?????? ???????? ???? ????? ?? ?????. What happen when these waves reaches the fixed point?They reflect.???? ???? ???? ??????? ????? ??? ????? ??????? ????? ???????.What happen when incidents waves and reflection waves meet each other????? ???? ????? ?????? ??????? ??????? ???????? ????????? They interfered and produce a standing wave.?????? ??????? ????? ??????? ????????.Standing wave will be formed, if two waves meet that are:of the same amplitudeof the same frequencytravelling in opposite directions.??????? ???????? ????? ????? ?????? ??????:???? ??? ????????? ??? ????????????? ?? ??????? ????????.331724010223513017532385 Standing waves on a string??????? ???????? ?? ?????If a string is plucked and allowed to vibrate freely, there are certain frequencies at which the string performs vibrations of large amplitude. This is known as a resonance effect.??? ???? ??? ?????? ???? ?????? ??? ???? ????? ??? ?????? ????? ???? ?????. ???? ??? ??????? ??????The following diagram shows the different standing wave forms and their wavelength and frequencies.????? ?????? ???? ??????? ???????? ?? ??????? ???????? ?? ?????? ?????????.The lowest resonant frequency is called the fundamental frequency or the first harmonic which produces a vibration with its greatest displacement at the mid-point of the string. ??? ???? ???? ?? ???? ???? ?????? ???? ?????? ???????? ?? ?????? ????????? ?????? ????? ???? ????? ???? ?? ???? ??? ????? ????? ?? ?????.Standing waves have nodes and antinodes. A node is a point where the displacement is zero. An anti-node is a point where the displacement is maximum.?????? ???????? ????? ?? ??? ????? . ??? ?????? ???? ??????? ????? ???. ???? ????? ???? ??????? ???? ?? ????. There is always a node at each fixed end of the string. ????? ????? ???? ??? ????? ??????.In a standing wave, all parts of the string between adjacent nodes vibrate in phase with each other, and that there is a phase difference of exactly half a cycle between parts of the string separated by a node.?? ?????? ????????? ???? ?????? ???? ??? ?????? ???? ????? ?? ?????. ???? ??? ?? ????? ?????? ??? ???? ??? ?????? ???? ?????? ????.Standing waves, in a musical string instrument, plucking the string gives rise to a large range of frequencies of vibration. Some of those frequencies match the fundamental and harmonic frequencies of the string, and these give rise to large-amplitude vibrations. The vibrations that make up standing waves on the string produce travelling waves in the air, which we hear as a musical note.??????? ???????? ?? ??????? ????????? ???????: ??? ?? ??? ???? ???? ??????? ??????. ??? ??? ???????? ?????? ?? ?????? ???????? ???????? ????????? ????? ??? ???? ????? ????? ????? ??? ??? ????????. ??????? ???????? ???? ????? ?? ????? ???? ????? ?????? ?? ?????? ??? ?????? ????? ???????. Standing waves in a tube??????? ???????? ?? ??????? ????????When you blow in a tube, the air inside it vibrates and gives out sound waves. The waves are longitudinal in the tube. When air vibrates in the tube, there is a displacement node at the closed end, whereas there is always a displacement anti-node at an open end of the tube. ??? ????? ?? ?????? ?????? ? ??? ?????? ?????? ???? ????? ???. ??????? ?? ??????? ???????? ?? ????? ?????. ????? ???? ?????? ?? ??????? ???????? ????? ???? ??? ????? ?????? ???? ??? ????? ???????.The diagram below shows the standing wave forms in tubes.????? ?????? ???? ??????? ???????? ??????? ???????? ?? ??????? ????????. Standing wave in wind instruments ??????? ???????? ?? ??????? ????????? ????????Blowing the mouthpiece of a wind instrument produces a wide range of frequencies, and the note produced contains the frequencies that correspond to the standing waves set up in the tube. ??? ????? ?? ??????? ????????? ???????? ???? ?????? ?? ????????. ??????? ???? ???? ?? ??? ??????? ????? ??? ?????? ???????? ???????? ????????? ??????? ????????. How do wind instruments work? ??? ???? ??????? ????????? ?????????Opening a hole in the side of a tube produces an anti-node at that position, hence opening and closing the holes produces notes of different frequencies. ??? ???? ?? ???????? ???????? ???? ??? ???? ??? ??? ??? ??????. ??? ???? ??????? ???? ??? ????? ????? ??????? ??????.-343535-150495Activity???? Measuring the speed of sound using resonance ???? ???? ????? ???????? ?????? Aim: To calculate the speed of sound in air.?????: ???? ???? ????? ?? ??????.Apparatus: ??????? Large measuring cylinder, glass tube open at both ends, set of tuning forks, meter rule.??????? ????? ?????? ?????? ??????? ?????? ?? ????? ???????? ????? ?????.Diagram: ?????Method: ????? ????? Hold the vibrating tuning fork above the glass tube. Move the tube up and down until you find the shortest length of the air column that produces a loud sound. Measure length “h”. Note the frequency of the tuning fork. Repeat this for tuning forks of several different frequencies.You have found the fundamental resonance length for the different frequencies. This is equal to ? of a wavelength. ?? ?????? ??????? ?? ???? ???????? ????????.??? ???????? ???????? ??? ???? ??? ??? ??? ????? ?????? ???? ???? ???? ???.??? ??? ???? ?????? ???? ???? ??????.??? ??????? ???????? ?????? ?? ????? ??????? ??? ???????? ????????.?? ????? ??? ???? ?????? ??? ???? . ???? ???? ???? ????? ?????? ??? ???? ?? ??????? ?????? L= 1/4 .FrequencyLength of air tubeWavelengthCalculate the speed of sound using the wave equation v = f for each frequency. Complete the following table.???? ???? ????? ??? ???? ?? ??????? v = f.FrequencyWavelengthSpeed of soundConclusion: ?????????Questions-510806-5740991- What is type of the wave in the following illustration??? ??? ?????? ???????? ?? ????? ???????2- What is the difference between a transverse wave and a longitudinal wave? ?? ????? ??? ?????? ??????? ??????? ????????? ? 3- Are sound waves transverse waves or longitudinal waves? Why??? ????? ????? ????? ?? ????? ??????? ? ??? ??? ??????4- The waves in A below are travelling across water.Are the waves transverse or longitudinal)What is the wavelength of the waves?What is the amplitude of the waves?If 2 waves pass the flag every second, what is i) the frequency ii) the period?Use the wave equation to calculate the speed of the waves in A.What is the wavelength of the waves in diagram B below?If the waves in B have the same speed as those in A, what is their frequency?9213855397599123537465??????? ?? ????? ?? ????? ??????- ?? ??????? ????? ?? ?????????- ?? ????? ?????? ???? ?????????-?? ??? ?? ??????- ??? ??? ?????? ????? ???? ????? ??? ????? ?????? ?????? ????????- ???? ???? ??????A?- ?? ????? ?????? ??????? ?? ????? B??- ??? ???? ???? ??????? ?? A,B ??????? ??? ????? ????????5- Refer to the drawing below to answer the following questions.Which of the lettered distances represents the wavelength of wave 1?Which of the distances represents the amplitude of wave 1?Which of the two waves has the greater wavelength?Which of the two waves has the smaller amplitude?Assuming that the two waves move at equal speed, which has the higher frequency?552450461645Assuming that the two waves move at equal speed, which has the greater period? ?? ????? ?????? ??? ?? ??? ???????.?- ?? ????? ???? ???? ????? ?????? ?????? 1??- ?? ??????? ???? ???? ????? ?????? 1??- ?? ???????? ????? ?????? ????? ?- ?? ???????? ????? ?????- ??? ???? ???????? ??????? ???? ?????? ?????? ??? ???? ??????- ??? ???? ???????? ??????? ???? ?????? ?????? ??? ???? ??? ?????6- A wave has a frequency of 2 hertz (2 cycles per second) and a wavelength of 10 cm.What is the speed of the wave????? ?????? 2 ????? ?????? ?????? 10cm ??? ???????7- A tuning fork creates sound waves with a frequency of 170 Hz. If the speed of sound in air is 340 m/s, calculate the wavelength of the sound waves.???? ????? ???? ????? ????? ?????? 170Hz ???? ???? ???? ????? ?? ?????? 340m/s , ???? ????? ?????? ?????? ?????.8- The speed of a transverse wave in a string is 15.0 m/s. If a source produces a disturbance that has a frequency of 5.00 Hz, what is its wavelength?9- Give an example which demonstrates each of the following:Sound can travel through a gas.Sound can travel through a liquid.Sound can travel through a solid.???? ????? ??????? ????? ??? ????? ??????? ??????10- Explain each of the following:Sound cannot travel through a vacuum.Sound waves are longitudinal waves.???? ????? ?? ????? ????? ??? ??????.????? ????? ??????? ??????? ?? ????? ?????.11- Assume that the speed of sound in air is 330 m/s.Why do you hear lightning after you see it?If lightning strikes, and you hear it 4 seconds after you see it, how far away is it????? ?? ???? ????? ?? ?????? ?? (330 m/s)?????? ???? ??? ????? ??? ???? ????????? ??? ?????? ??????? ??? ???? ????? ?? ?????? ?? ??? ???? ????? ????12- Does sound travel faster through: cold air or warm air? a solid or a gas??? ????? ????? ???? ?? ?????? ?????? ?? ?????? ?????????? ????? ????? ???? ?? ?????? ?????? ?? ?? ?????? ?????????13- Draw a labeled diagram showing a string vibrating at three times its fundamental frequency. Label the nodes and antinodes. Show which parts of the string are vibrating in phase with each other, and which half cycles out of phase are.???? ????? ???? ?????? ??? ????? ????? ????? ????? ?????? ???????? ?????. ??? ??? ????? ????? ???????. ?????? ??????? ?? ?????. ?????? ???? ????? ??? ?? ????? ?????? ??? ????. 13- One student plays a note on a string instrument and another plays a note of the same pitch on a wind instrument. Explain why the notes sound different.???? ???? ????? ?? ???? ??????? ????? ????? ??? ???? ???? ???? ?????? ?? ???? ??????? ??????. ???? ????? ???? ????? ??????? ??????.14-In the diagram below, the air in the pipe is vibrating at its fundamental frequency.0.3 mShow the positions of any nodes or antinodes.What is the wavelength of the sound coming from the pipe?If the speed of sound in air is 330ms-1, what is the frequency of the sound coming from the pipe?If the pipe was double the length, what would its fundamental frequency be?If the pipe (at the original length) was open at both ends, what would its fundamental frequency be??? ????? ??????? ?????? ???? ?? ???????? ????? ?????? ????????.??? ??? ????? ????? ??????? ???????? ?? ??? ??????.?? ?? ????? ?????? ?????? ???????? ?? ?????? ??????????? ???? ???? ????? ?? ?????? ????? 330ms-1 . ?? ?? ???? ?????? ???????? ?? ???????????? ???? ??? ???????? ??? ?????? ?? ?? ???? ?????? ???????? ?? ??? ?????????? ???? ???????? ??? ?????? ?????? ??????? ???? ????? ??????? ?? ?? ???? ?????? ?????????4877435-54610Resources:Books: 1- Complete physics (Stephen Pople)2- Longman GCSE physics (Brin Arnold . Steve Woolley)3- GCSE Physics ( Tom Duncan & Heather Kennett) 4-Glencoe Physics (Paul W .Zitzewitz)5- Holt Physics (Raymond A. Serway, Ph.D., Jerry S. Faughn, Ph.D.) ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download