Sound Waves Powerpoint

Audible:

20 to 20,000 Hz

ultrasound:

> 20,000 Hz

____ variables are: Pressure Density Distance

Acoustic

We said that sound needs a medium to propagate. Do the electromagnetic waves need a medium too?

Electromagnetic waves do not require a medium for propagation.

every point on a wave front serves as a source of spherical secondary wavelets

Huygens Principle

___ waves travel slower and are produced by the moon's gravitational force on earth.

Ocean

___ waves and _____ waves are mechanical waves

Ocean , sound

Acoustic Variables are:

Pressure, Density, and Particle vibration (distance)

____ travel at the speed of light and do not need a medium for propagation.

Radiowaves

___ and _____ waves are mechanical waves

Sound , ultrasound

_____ ______ ___ ____ ____ ___ ___: it is a wave that vibrates and it has the capacity to do work.

Sound is a vibratory form of energy

What is the difference between sound waves and x-ray waves?

X-Rays are electromagnetic waves and sound waves are mechanical

These three quantities are defined as _____ _____

acoustic variables

Sound waves of human speech are mechanically produced by the deformation of ___ caused by vibrations of the vocal cords in the larynx.

air

In longitudinal waves, particles move "___" the same direction as the wave.

along

____ (20 to 20,000 cycles/sec)

audible

Fundamentals of Waves:

audible, ultrasound, and infrasound

The particles move ___ and ____ in the direction of propagation of the wave.

back , forth

Longitudinal waves are made up of areas of _____ (also called condensation) and areas of ____.

compression , rarefaction

The vibrations cause alternating _____ and ____ in the particles of the medium.

compressions , rarefactions

Mechanical waves propagate energy through a medium by ___ ___ ____.

cyclic pressure variation

They need a ___, ___ ___ like air, water, or soft tissue.

deformable , elastic medium

____: Concentration of mass in a volume. Units: kg/cm 3

density

The speed of sound through a medium depends on the medium's ___, ___, and ____

elasticity, density, and temperature.

Examples of other ____ waves: radiowaves, radar, gamma, ultraviolet, infrared, visible light, microwaves, etc.

electromagnetic

Radiowaves are ___ waves

electromagnetic

The ____ in the mechanical wave is transmitted through the motion of these particles.

energy

True or false: Since we really do not image through developed bone, we do use transverse waves in diagnostic ultrasound.

false, do not

The ___ of a sound wave is the number of compressions (or rarefactions) that pass a fixed point per unit time.

frequency

When these wavelets combine they have an ___ ____ appearance

hour glass

____ (< 20 cycles/sec)

infrasound

when two or more waves combine to form a single wave

interference

Sound propagates through air or other mediums as a ____ wave, in which the mechanical vibration constituting the wave occurs along the direction of propagation of the wave.

longitudinal

At any point in the medium, pressure and density go through cycles of increase and decrease of the sound wave as this travels in the medium creating regions of ___ pressure or rarefactions and regions of ____ pressure or compressions.

low , high

Sound involves ____ motion in the medium through which it travels.

mechanical

Sound is something that travels through a ___.

medium

_____: means a media with mass and molecules in order for sound to travel

medium

___ ____ is defined as one type of wave motion being converted to the other.

mode conversion

Fully ____ bone is the only biological tissue that can cause production of transverse waves

ossified

___ ___: (Distance) Units: cm, ft, mile.

particle motion

The wave travels through the medium by the progressive interaction of individual _____ as they oscillate back and forth.

particles

In a transverse wave, the motion that constitutes the wave is ____, or transverse, to the direction in which the wave is moving.

perpendicular

In transverse waves, particles vibrate "____" to the direction of the wave form.

perpendicular

Along with changes in ___ gradients in a wave sound, there are other variations in density (defined as the concentration of mass in a volume), and in vibration of the particles in the medium.

pressure

Sound waves are longitudinal (sometimes called ____ waves).

pressure

That "something" is traveling variations in ____.

pressure

___ is an acoustic variable because it varies with time as the wave moves through the medium.

pressure

___: Concentration of force in an area. Units: pascals (Pa)

pressure

Sound can be described as periodic changed in the pressure of medium so they can also be called "___ waves or ___ waves"

pressure , compression

Sound is a mechanical form of energy and requires a medium in order to ____

propagate

The created wavelets will have the ____ frequency and speed as the original

same

Ultrasound, infrasound, and audible sound have the ____ properties.

same

A ___ wave is generated by a vibrating object.

sound

Acoustic Variables allow to IDENTIFY ____ waves from other types of waves.

sound

Ultrasound is a form of ___.

sound

___ waves (not used in ultrasound). Some waves are not simply longitudinal or transverse. Such are classified as surface waves (particle movement restricted to a thin layer at the surface of the medium supporting the waves

surface

A wave of energy is ____ from one location to another when vibrating molecules interact with neighboring molecules

transmitted

Examples of ____ waves are: electromagnetic sources such as light or radio, in which the electric and magnetic fields constitute the wave oscillating perpendicular to the direction of propagation

transverse

______ waves (shear waves).

transverse

There are two basic types of wave:

transverse; longitudinal

True or false: The medium itself does not move from one place to another.

true

constructive interference

two in-phase waves form a single wave of greater amplitude

destructive interference

two out-of-phase waves form a single wave of lesser amplitude

____ (> 20,000 cycles/sec)

ultrasound

Sound needs a medium, it cannot be in a ____

vacuum

A wave is a traveling ____ in one or more quantities, such as pressure.

variation

Pressure variations cause the particles in the medium to ___.

vibrate

Sound is a ___.

wave

Remember Frequency: 1 cycle /sec 1 Hz Unit 1,000 cycles / sec 1kHz

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Remember: An area of COMPRESSION is an area of HIGH PRESSURE.

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Remember: Audible sound: 20 Hz to 20,000 Hz ; or 20 Hz to 20 kHz

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Remember: Electromagnetic waves are ALL transverse waves.

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Remember: Mechanical waves can be either transverse or longitudinal waves.

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Remember: Ultrasound waves are longitudinal waves

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Remember: If any one of these Acoustic Variables oscillates rhythmically the wave is a sound wave.

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Remember: sound waves cannot be transmitted in a vacuum.

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Remember: A HIGH PRESSURE area is called COMPRESSION, CONDENSATION, A PEAK, OR ANTI-NODE.

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Remember: A LOW PRESSURE area is called RAREFACTION, A VALLEY, OR A NODE.

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Remember: An area of RAREFACTION is an area of LOW PRESSURE.

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Remember: Ultrasound: > 20,000 Hz , or > 20kHz

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Remember: With waves of different frequencies both constructive and destructive interference occurs at some point

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Remember: Sound is not an electromagnetic wave

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Remember: sound is mechanical form of energy, requires a medium to propagate, and has the capacity to do work

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Remember: Infrasound: < 20 Hz

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Remember: Sounds are all mechanical waves.

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Frequency expressed in cycles / sec: _______

1 cycle / sec = Hertz (Hz)