Define the wave nature of sound, Physics

Assignment Help:

Define the Wave Nature of Sound

Sound is called a longitudinal wave because the vibrations are in the same direction as the motion and speed of the wave. This is most easily pictured if you imagine a SlinkyTM stretched lightly across a tabletop. If your friend holds the far end and you pinch together a bunch of Slinky and quickly release the loops, you will see a longitudinal wave move across the Slinky. The vibration and the wave travel in the same direction, from you to your friend, across the table.

757_Wave Nature of Sound 1.png

Sound is created by the alternating compression and expansion of air. Sound travels at a speed of 331 m/s in air at 0oC. The speed increases as the temperature of the air increases, at a rate of 0.6 m/s per Celsius degree. If something moves faster than sound, it is said to be supersonic. If it travels at the speed of sound, it travels at Mach 1; three times the speed of sound is called Mach 3.

The pitch of a sound is related to its frequency. A higher frequency sound has a higher pitch. Frequencies of sound waves that humans can hear range from about 20 - 20,000 hertz or cycles per second. Longitudinal waves that have higher pitch or frequency than humans can hear are called ultrasonic. Ultrasonic sound is used in sonar systems. The loudness of the sound is related to the wave's energy or intensity.

When two sound waves of slightly different frequency are added together, the resultant sound wave will have periodically changing loudness, known as the beat. The frequency of the beat is the difference in the two frequencies, and the frequency of the resultant sound is the average of the two frequencies. 

 

1587_Wave Nature of Sound 2.png

Loudness and sound intensity can be confusing, because loudness is a measurement based on the sensation caused in a human by sound intensity. Because the human ear is sensitive over a very large range of intensity, loudness is defined using a logarithmic scale. (As pocket calculators have become more and more common and slide rules are used less and less, people have much less experience and comfort using logarithms.) A sound wave that is twice as loud has roughly ten times the intensity.

1095_Wave Nature of Sound 3.png

where b is the loudness measured in decibels (dB), I is the intensity of the sound wave in watt/m2 and Io is a constant equal to 1 x 10-12 watt/m2. Io represents the most faintly heard sound by humans and is defined as the loudness of 0 dB. Just as for gravity, electricity and magnetism, the intensity of sound drops off as the inverse square of the distance from the source.


Related Discussions:- Define the wave nature of sound

Earths rotation about its axis, The earth's rotation about its axis changes...

The earth's rotation about its axis changes measurably over time; You don't have to worry about the details; all you need to know is that our days are growing longer by about 2.3 m

Calculate the radius - protein with a density, 1.  A protein with a density...

1.  A protein with a density of 1.41 g/cm 3 has a molecular weight of 5000 g/mol. a. Calculate its radius. b. The radius measured during an experiment turned out to be 2.24

One would expect proton to have very large, One would expect proton to have...

One would expect proton to have very large: (1) Ionization potential (2) Radius (3) Charge (4) Hydration energy Ans:(4) Hydration energy

Explain frictionless horizontal surface, A block of mass 10 kg is attached ...

A block of mass 10 kg is attached to the end of a horizontal spring with spring constant k = 1200 Nm-1. The block is assumed to be sitting on a frictionless horizontal surface.

Explain width of principal maxima and intensity, Two grating A and B have t...

Two grating A and B have the same width of the ruled surface but A has greater number of lines. Giving reasons compare in two cases (a) Intensity (b) Width of principal maxim

Is mechanical energy preserved in process, A disk defamation horizontally o...

A disk defamation horizontally on a frictionless, mass less, rotational motion support such that the disk is spinning freely about a vertical axis through the centre of the disk an

Explain centrifugal force, Feeling centrifugal force Tie a weight to a...

Feeling centrifugal force Tie a weight to a string about a metre in length and then whirl the weight around at arm's length. View the outward pull on the string. This is centri

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd