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# Analysing sound waves

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### Analysing sound waves

1. 1. ANALYSING SOUND WAVES
2. 2. THE NATURE OF SOUND WAVES  Sound is a form of energy propagated as waves that make our eardrums vibrate.  Sound waves are longitudinal waves which is required a medium for its propagation.  Sounds are produces by vibrations such as the vibrations of the coneshaped diaphragm of loudspeaker, guitar strings, column of air in a musical instrument a tuning fork  Sound waves cannot travel in a vacuum because there is no medium(particles) through which the sound energy can be propagated.
3. 3. How is sound produced by a vibrating objects?  When a tuning fork vibrates, layers of air vibrate and the sound energy is propagated through the air around it in the form of waves.  • When the tuning fork moves forwards, the air is compressed.  • When the tuning fork moves backwards, the air layers are pulled apart and cause a rarefaction.  • Therefore, a series of compression and rarefactions will produce sound. 
4. 4. Why does sound waves is a longitudinal waves?  The air particles vibrate backward and forward in the direction parallel to the direction of propagation of the sound wave.  • Wavelength of sound, λ = the distance between two successive regions of compression or two successive regions of rarefaction.
5. 5. SPEED OF SOUND Sound waves travel faster in solid > liquid > gas
6. 6. LOUDNESS & AMPLITUDE OF SOUND  The loudness of a sound is considered to be high or otherwise depending on the hearing ability of a person.  Loudness is influenced by the amplitude of the sound wave.
7. 7. PITCH & FREQUENCY OF SOUND  The pitch of a sound or a musical note is an indication of how high or low the sound is.  The pitch of a sound is determined by its frequency : a high pitch corresponds to a high frequency.
8. 8. A P P L I C AT I O N S O F S O U N D WAV E S  Cleaning with Ultrasonic Waves - Dentist use ultrasonic waves to removes plaque from teeth  Locating an object under water - SONAR is a system used to detect underwater objects or to determine the depth of the water by mean of an echo. - Ultrasound signal is sent out from a transmitter. - Its echo from the seabed is detected by a receiver which is connected to an electrical recording circuit. - The time interval, t between the sending and receiving of the ultrasound signal after reflection from the seabed is measured.
9. 9.  Disintegration of kidney stones - sound waves of high energy are directed at the kidney stones to destroy them in the cavity of the kidney.  A bat can navigate in darkness  When ultrasonic waves emitted by the bat hit an object, they are reflected back and received by the bat.  The time between the emission of the sound waves and reception of the reflected waves enables the bat to estimate the position of the object accurately.  This enables the bat to adjust its direction to avoid knocking at the object.
10. 10. CALCULATING DISTANCES USING THE REFLECTION OF SOUND WAVES
11. 11. EXAMPLE 1. a student is standing at a distance of 45 m from a wall. He gives loud clap and the echo is heard after 0.3 s, calculate the speed of sound in air.
12. 12. An ultrasonic wave is used to determine the depth of a seabed. A pulse of ultrasound is generated and travels to the seabed and reflected by it. The time taken by a pulse of ultrasonic wave to travel to and fro the seabed is 0.28 s. It the speed of sound in the water is 1 500 ms-1, calculate the depth of the seabed.