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# Sound

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A Report made by me and group in physics course.

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### Sound

1. 1. 9/7/2013 Newports Institute of Communication & Economics SOUND REPORT Submitted To: Miss Faryal Submitted By: Muhammad Saqib Ishaq Zuhaib Ali Abdul Ahad Sheikh
2. 2. Final Report on Sound Newports Institute of Communication & Economics 2 | P a g e Table of Contents Introduction of Sound ...........................................................................................3 Pitch of Sound....................................................................................................3 Speed of Sound ..................................................................................................4 Frequency of Sound...........................................................................................5 The Doppler Effect................................................................................................5 Examples of Doppler Effects.............................................................................5 Intensity of Sound.................................................................................................6 Unit of Sound Intensity......................................................................................6
3. 3. Final Report on Sound Newports Institute of Communication & Economics 3 | P a g e Introduction of Sound Sound is one kind of longitudinal wave, in which the particles oscillate to and fro in the same direction of wave propagation. Sound waves cannot be transmitted through vacuum. The transmission of sound requires at least a medium, which can be solid, liquid, or gas. Pitch of Sound Pitch is the frequency of a sound as perceived by human ear. A high frequency gives rise to a high pitch note and a low frequency produces a low pitch note.
4. 4. Final Report on Sound Newports Institute of Communication & Economics 4 | P a g e Speed of Sound The speed of sound is the distance travelled during a unit of time by a sound wave propagating through any medium. The speed of sound in air actually depends on the temperature of the air. In dry air at 20 °C, the speed of sound is 343.2 m/s. This is 1,236 km/h, or about a kilometre in three seconds. The formula to calculate the speed of sound at a different temperature is as below. V = 331.5m/s + 0.6T Where: V = velocity of sound in m/s T = temperature in °C Speed of Sound in different Material Material Speed of Sound Rubber 60 m/s Air at 40o C 355 m/s Air at 20o C 343 m/s Lead 1210 m/s Gold 3240 m/s Glass 4540 m/s Copper 4600 m/s Aluminum 6320 m/s
5. 5. Final Report on Sound Newports Institute of Communication & Economics 5 | P a g e Frequency of Sound Frequency of Sound is characterized as a periodic vibration whose frequency is audible to the average human. The formula to calculate the Frequency of Sound is as below. v = f λ Where: v = speed in meters/second (m/s) f = frequency in Hertz (Hz) λ = wavelength in meters (m) If the sound you are measuring is at a constant temperature then the velocity will be constant about 340 m/s. The Doppler Effect Doppler Effect is the apparent change in the frequency of a sound caused by the motion of either the listener or the source of the sound. Examples of Doppler Effects Imagine that you are standing on a corner as an ambulance rushes by. As the ambulance passes, the sound of the siren changes from a high pitch to a lower pitch. Why? Do the sound waves produced by the siren change as the ambulance goes by? How does the motion of the ambulance affect the sound?
6. 6. Final Report on Sound Newports Institute of Communication & Economics 6 | P a g e Intensity of Sound Sound intensity is defined as the sound power per unit area A. The formula to calculate the Sound Intensity is as below. I = PA Where: I = Intensity P = Pressure of sound, A = Area The intensity of sound decreases with the distance from the source of sound. The intensity of sound depends on:  Amplitude of vibrations of the source.  Surface area of the vibrating source.  Distance of the source from the observer.  Density of the medium in which sound travels form the source.  Presence of other surrounding bodies and  The Motion of the medium. Unit of Sound Intensity The units for sound intensity in S.I system is (watts per square metre) W/m2 . It is a physical quantity.