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© Boardworks Ltd 2004 Waves: Sound IGCSE Physics
© Boardworks Ltd 2004 Waves: Sound Contents What is sound? Sound and reflection Hearing sound Ultrasound Structure of sound waves
© Boardworks Ltd 2004 Aims Describe the production of sound by vibrating sources. Describe the longitudinal nature of sound waves. Show an understanding that a medium is required in order to transmit sound waves. Describe an experiment to determine the speed of sound in air.
© Boardworks Ltd 2004 What causes sound? The tuning fork vibrates and you hear a sound. Sounds are made when an object vibrates. Take a tuning fork and strike it against a block of wood. What do you observe?
© Boardworks Ltd 2004 Good vibrations! What vibrates so that the following make sounds? violin strings drum skin voice box loudspeaker cone
© Boardworks Ltd 2004 How does sound travel? How does sound reach your ear? When the drum skin is struck, it vibrates which causes the air beside the drum to vibrate. The compression and stretching of air particles creates a sound wave which is carried through the air to your ear. What type of wave is a sound wave? longitudinal wave
© Boardworks Ltd 2004 Remove the air from the bell jar and what happens to the sound? The bell-jar experiment Place a ringing clock inside the bell jar and what happens? There is air inside the bell jar so the sound can travel and be heard. With a vacuum inside the bell jar, the sound cannot be heard. Why? vacuum pump on
© Boardworks Ltd 2004 100 m START STOP 1. When you see the cymbals crash, press START. 2. When you hear the cymbals crash, press STOP. You need a quiet open space at least 100 m long to perform this investigation. How fast does sound travel?
© Boardworks Ltd 2004 sound distance (m) time (s) speed (m/s) 1 2 3 4 How are these values used to estimate the speed of sound? Record the results of your sound experiments in a table. =294 m/s distance time speed = = 100 0.34 100 0.34 294 How fast does sound travel?
© Boardworks Ltd 2004 Use the results of the cymbals experiment to calculate your average speed of sound. How does your calculation for the average speed of sound compare with the real speed? The speed of sound in air is about… What errors could have affected the results of your cymbals experiment? 340 m/s Do you think the speed of sound in water is the same as it is in air? How fast does sound travel?
© Boardworks Ltd 2004 Different speeds of sound
© Boardworks Ltd 2004 Sound and states of matter Sound waves need a substance to travel through. What are all substances made of? What is the particle model of a solid, a liquid and a gas? In which state are the particles closest together? In which state are the particles furthest apart? solid gas particles solidgasliquid
© Boardworks Ltd 2004 Sound and states of matter Sound waves travel by particles vibrating. What state does sound travel fastest through and why? The particles in a solid are closer together than in a gas or a liquid. This means vibrations are more easily passed from particle to particle and so sound waves travels faster. solidgasliquid Sound waves travel fastest through solids.
© Boardworks Ltd 2004 Usually, you see lightning before you hear thunder. Light travels much faster than sound. The speed of light is… During a thunderstorm, thunder and lightning are created at the same time. Which do you notice first? How could you use thunder and the speed of sound to estimate how far away a thunderstorm is? 300 000 000 m/s How much faster is light than sound? Sound or light – which is faster?
© Boardworks Ltd 2004 Which of these travel faster than the speed of sound in air? distance (m) time (s) speed (m/s) small aeroplane 6005 jet fighter9002 cheetah502.5 meteorite10 0000.35 120 450 28 571 20 The jet fighter and the meteorite break the sound barrier. What does this mean? Breaking the sound barrier!
© Boardworks Ltd 2004 Waves: Sound Contents What is sound? Hearing sound Ultrasound Structure of sound waves Sound and reflection
© Boardworks Ltd 2004 Aims Describe how the reflection of sound may produce an echo.
© Boardworks Ltd 2004 The sound wave is reflected back from the surface. What type of sound does this produce? What happens when a sound wave meets a hard flat surface? echo Reflected sound waves
© Boardworks Ltd 2004 1. Use a starting pistol (or clapper board) to make a sound. 2. Measure the time taken between firing the pistol and hearing the echo. How far does the sound travel? START 150 m Stand at least 100 m from a large, flat wall with a stop watch. STOP Experiment on echoes
© Boardworks Ltd 2004 How can you use this result to estimate the speed of sound? The sound of the starting pistol takes 0.92 s to travel a distance of 300 m. =326 m/s distance time speed = = 300 0.92 Repeat the experiment several times to obtain an average. How does your calculation for the average speed of sound compare with the real speed? Experiment on echoes
© Boardworks Ltd 2004 Echoes and reflection What do we call reflected sound?an echo Are hard or soft surfaces best at reflecting sound? How are echoes reduced in cinemas and theatres? By using soft materials on the walls such as curtains. Name two animals that use echoes for navigation or communication. bats and dolphins Hard surfaces produce strong echoes.
© Boardworks Ltd 2004 Waves: Sound Contents What is sound? Structure of sound waves Hearing sound Ultrasound Sound and reflection
© Boardworks Ltd 2004 Aims State the approximate range of audible frequencies. Relate the loudness and pitch of sound waves to amplitude and frequency.
© Boardworks Ltd 2004 Sound waves can be studied with this type of equipment. loudspeaker signal generator oscilloscope Which piece of equipment… produces signals over a range of frequencies and of varying amplitudes? converts signals into sound waves? is used to study the frequency and loudness of a sound? signal generator oscilloscope loudspeaker Studying sound waves
© Boardworks Ltd 2004 loud sound quiet sound What is the difference between the sound wave of a quiet sound and a loud sound? The loud sound has taller waves. What would the sound wave of a very loud sound look like? The louder the sound, the greater the amplitude. Why sound is quiet or loud?
© Boardworks Ltd 2004 Which is the loudest? Sound A is the loudest. Which trace represents the loudest sound? Sound A has the largest amplitude, which means the wave has more energy and so the sound is louder. AB
© Boardworks Ltd 2004 low pitch sound high pitch sound What is the difference between the sound wave of a low pitch sound and a high pitch sound? The high pitch sound has a shorter wavelength, so more waves are visible. It has higher frequency waves. What would the sound wave of a very low sound look like? Why sound is low pitch or high pitch?
© Boardworks Ltd 2004 Which is the highest? Which trace represents the sound with the highest pitch? Sound B is the highest pitched. Sound B has the shortest wavelength and the most number of waves visible, so it has the highest frequency. BA
© Boardworks Ltd 2004 Wave animation
© Boardworks Ltd 2004 Waves: Sound Contents What is sound? Hearing sound Ultrasound Structure of sound waves Sound and reflection
© Boardworks Ltd 2004 1.Sound waves are collected by the ear lobe or pinna. 2.The waves travel along the ear canal. 3.The waves make the ear drum vibrate. 4.The small bones (ossicles) amplify the vibrations. 5.The cochlea turns these into electrical signals. 6.The auditory nerve takes the signals to the brain. 3 4 5 6 1 2 How does the ear hear?
© Boardworks Ltd 2004 How does the ear hear?
© Boardworks Ltd 2004 Set the volume and increase the frequency of the signal provided by the signal generator. 20 Hz to 20 000 Hz Humans cannot hear sounds of every frequency. What is the hearing range of a healthy young person? The range of frequencies you can hear is called your hearing range. Can we hear all frequencies?
© Boardworks Ltd 2004 We all have slightly different hearing ranges but almost 1 in 5 people suffer some sort of hearing loss. Temporary hearing loss may be caused by ear infections and colds after which hearing recovers. Permanent hearing loss and deafness can be present at birth or occur if the ear is damaged or diseased. Does everyone have the same hearing range? People lose the ability to hear sounds of high frequency as they get older. Which end of their hearing range will be affected? Do we have the same hearing?
© Boardworks Ltd 2004 100 000 10 000 1 000 100 10 1 0 human dog elephant bat mouse dolphin Do all animals have the same hearing range? frequency (Hz) Comparing hearing ranges
© Boardworks Ltd 2004 The results of a hearing tested are shown on an audiogram. It records the softest sound heard at each pitch. The audiogram shows hearing sensitivity for different frequencies (pitch) at different intensities (volume). frequency of sound (Hz) intensity of sound (dB) loud sound moderate sound soft sound low pitch high pitch How is hearing tested?
© Boardworks Ltd 2004 Which audiogram trace represents optimal hearing and which represents impaired hearing? optimal hearing impaired hearing frequency of sound (Hz) intensity of sound (dB) Testing hearing
© Boardworks Ltd 2004 Waves: Sound Contents What is sound? Hearing sound Structure of sound waves Sound and reflection
© Boardworks Ltd 2004 Sound multiple choice
© Boardworks Ltd of 20 © Boardworks Ltd of 36 KS3 Physics 8L Sound and Hearing.
© Boardworks Ltd of 20 © Boardworks Ltd of 40 KS3 Physics 8L Sound and Hearing.
1 of 36© Boardworks Ltd of 36 3 of 36© Boardworks Ltd 2007 What causes sound? The tuning fork vibrates and you hear a sound. Sounds are made.
© Boardworks Ltd 2004 Waves: Sound KS4 Physics. © Boardworks Ltd 2004 Waves: Sound Contents What is sound? Sound and reflection Hearing sound Ultrasound.
1 of 40© Boardworks Ltd of 40 3 of 40© Boardworks Ltd 2008 What causes sound? The tuning fork vibrates and you hear a sound. Sounds are made.
© Boardworks Ltd of 46 Sound KS4 Physics. © Boardworks Ltd of 46 Sound Contents What is sound? Hearing sound Ultrasound Structure of sound.
© Boardworks Ltd 2003 A slide contains teacher’s notes wherever this icon is displayed - To access these notes go to ‘Notes Page View’ (PowerPoint 97)
1 of 40© Boardworks Ltd 2008 What causes sound? The tuning fork vibrates and you hear a sound. Sounds are made when an object vibrates. Take a tuning fork.
Understand that sound waves are produced by vibrating objects, and that sound requires a medium to travel through. Understand the links between amplitude,
© Boardworks Ltd 2004 Using Sound KS4 Physics. Learning Objectives Understand how sound is heard and the audible frequencies of human hearing Understand.
Sound What is sound? It is made when an object or material vibrates. A vibration is a fast, backwards and forwards movement that repeats many times.
IGCSE Physics Sound. Aims: To describe how to measure the speed of sound in air by a simple direct method. To use an oscilloscope to determine the frequency.
© Boardworks Ltd 2003 KS4 Waves : Sound. © Boardworks Ltd 2003 A slide contains teacher’s notes wherever this icon is displayed - To access these notes.
Sound Vibrations Loudness Pitch and frequency Echoes.
Sound Production of sound by vibrations The tuning fork vibrates and you hear a sound. Sounds are made when an object vibrates. Sounds is a form.
Sound How is Sound Made? Demo – Play your musical instrument What caused the sound? Demo – Tuning Fork The tuning fork vibrates and you hear a sound.
PHYSICS – Sound. LEARNING OBJECTIVES Core Describe the production of sound by vibrating sources Describe the longitudinal nature of sound waves State.
© Boardworks Ltd 2003 What causes sound? Take a tuning fork and strike it against a block of wood, what do you observe? The tuning fork vibrates and you.
Unit 2 Lesson 1 Sound Waves and Hearing Copyright © Houghton Mifflin Harcourt Publishing Company.
SOUND WAVES. GUIDELINES Light and sound understand that sound waves are longitudinal waves which can be reflected, refracted and diffracted know that.
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Vibrations Sound waves are compression waves. They are made of atoms being pushed, or compressed, by other atoms. Why wouldn’t sound waves carry in space?
- Sound. Sound is a form of energy that travels through matter as waves.
Copyright © Houghton Mifflin Harcourt Publishing Company What are sound waves? A sound wave is a longitudinal wave that is caused by vibrations and that.
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A repeating movement or disturbance that transfers energy... …through matter …or through space.
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1) Determine the wave speed of a wave that has a period of 3 minutes and a wavelength of 0.05 m. 2) How are electromagnetic and mechanical waves different?
Resonance: occurs when an object absorbs energy from vibrations that are at its natural frequencies If one tuning fork is struck, its vibrations will.
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