Chapter 12 Review

Explain how waves are produced

Vibration of an object is what produces sound waves. The vibrating object moves in one direction and compresses the air directly in front of it. As the vibrating object moves in the opposite direction, the pressure on the air is

lessened so that an expansion or rarefaction of air molecules occurs.

http://www.youtube.com/watch?v=XLfQpv2ZRPU

Relate frequency to pitch

Pitch is quality of a sound governed by the rate of vibrations producing it while frequency is the rate at which a vibration occurs that constitutes a

wave

http://www.youtube.com/watch?v=YTZcSaPn92s

Compare the speed of sound in various media

The speed of sound depends on the material through which it is passing. It’s greater in solids than in liquids or gases because the molecules in a solid are

closer than liquids or gases

http://www.youtube.com/watch?v=Au1NkDy_dkU

Relate plane waves to spherical waves

A plane wave is a wave of a constant frequency and amplitude with wave fronts that are an infinitely long straight line. Plane waves travel in the

direction perpendicular to the wave fronts. Although they are a mathematical abstraction, many physical waves approximate plane waves far from their

source.

http://www.youtube.com/watch?v=x72lNmsDrJE

Recognize the Doppler effect, and determine the direction of a frequency shift when there is relative

motion between a source and an observer The Doppler Effect is an increase or decrease in the frequency of sound, light, or other waves as the source and observer move toward or away from each other. The effect causes the sudden change in pitch noticeable in a passing

siren, as well as the redshift seen by astronomers.

The frequency of a wave-like signal - such as sound or light - depends on the movement of the sender and of the receiver.

http://www.youtube.com/watch?v=h4OnBYrbCjY

Calculate the intensity of sound waves

Sound waves are introduced into a medium by the vibration of an object. For example, a vibrating guitar string forces surrounding air molecules to be

compressed and expanded, creating a pressure disturbance consisting of an alternating pattern of compressions and rarefactions. The disturbance then travels from particle to particle through the medium, transporting energy as

it moves. The energy that is carried by the disturbance was originally imparted to the medium by the vibrating string. The amount of energy that is transferred to the medium is dependent upon the amplitude of vibrations of the guitar string. If more energy is put into the plucking of the string (that is,

more work is done to displace the string a greater amount from its rest position), then the string vibrates with a greater amplitude. The greater

amplitude of vibration of the guitar string thus imparts more energy to the medium, causing air particles to be displaced a greater distance from their

rest position. Subsequently, the amplitude of vibration of the particles of the medium is increased, corresponding to an increased amount of energy being

carried by the particles.

Relate intensity, decibel level, and perceived loudness

According to Google definitions, intensity is the measurable amount of a property, such as force, brightness, or a magnetic field.

Decibel level is unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic

scale.Perceived loudness is how loud it appears to be to the active listener.

http://www.youtube.com/watch?v=rz1CIf-MgFo

Explain why resonance occurs

Resonance is the quality in a sound of being deep, full, and reverberating.Frequencies at which the response amplitude is a relative maximum are known as the system's resonant frequencies, or resonance frequencies.

Resonance occurs when a system is able to store and easily transfer energy between two or more different storage modes

http://www.youtube.com/watch?v=ZzHajoDf1fg

Sources:

• http://www.einstein-online.info/spotlights/doppler• http://www.physicsclassroom.com/class/sound/u11l2b.cfm• https://www.google.com/#q=definition+of+intensity• https://www.google.com/?gws_rd=ssl#q=what+is+resonance• http://en.wikipedia.org/wiki/Resonance