Sound Waves Chapter 12 Section 1

Sound Waves Chapter 12 Section 1

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The Production of Sound Waves

Sound produces longitudinal waves composed of compressions and rarefactions.

Multiple Choice

Sound waves produce

• sine waves

• transverse waves

• longitudinal waves

• electromagnetic waves

Longitudinal Waves

• Compression -- the region of a longitudinal wave in which the density and pressure are at a maximum.

• Rarefaction -- the region of a longitudinal wave in which the density and pressure are at a minimum.

Compressions and Rarefactions

As this tuning fork vibrates, a series of compressions and rarefactions moves away from each prong. The crests of this sine wave corresponds to compressions and troughs correspond to rarefactions.

Multiple Choice

The areas of compression in a longitudinal wave correspond to the ________________ of a transverse or sine wave.

• troughs

• crests

• wavelength

• frequency

Multiple Choice

The areas of rarefaction in a longitudinal wave correspond to the ________________ of a transverse or sine wave.

• troughs

• crests

• amplitude

• frequency

Characteristics of Sound Waves

Sound waves that the average human ear can hear, called audible sound waves, have frequencies between 20 and 20, 000 Hz.

Multiple Choice

The normal human range of hearing is between

• 10 and 15,000 Hz

• 30 and 30,000 Hz

• 1000 and 40,000 Hz

• 20 and 20,000 Hz

Characteristics of Sound Waves cont.

Sound waves less than 20 Hz are infrasonic waves and are outside the range of human hearing. Large animal such as elephants and whales communicate with these sounds. These sounds can travel long distances.

Multiple Choice

The sound range of frequency too low for human hearing is called

• ultrasonic

• infrasonic

• supersonic

Characteristics of Sound Waves cont.

Sound waves with frequencies above 20,000 Hz are called ultrasonic waves. Animals such as dogs, cats, and bats can hear in the ultrasonic range.

Ultrasound Waves

Ultrasound waves are also used in medical devices to produce images and medical treatment. .

Ultrasonic Waves

Ultrasonic waves can be used for echo location.

Multiple Choice

The frequency of sound that has a pitch too high for human hearing is called

• infrasonic

• ultrasonic

• supersonic

Frequency Determines Pitch

Pitch is a measure of how high or low a sound is perceived to be, depending on the frequency of the sound.

Multiple Choice

A sound wave of high frequency has a high

• pitch

• crest

• wavelength

The Speed of Sound

The speed of sound waves depends on the medium it passes through. Sound travels faster through solids because the molecules are closer together. Sound travels slower through air because the gas particles are farther apart.

Multiple Choice

Sound travels fastest through

• space

• solids

• liquids

• gases

Sound Waves Propagate in Three Dimensions

Sound waves travel away from a vibrating source in all three dimensions. The waves produced are spherical waves.

The Doppler Effect

Relative motion creates a change in frequency. As the ambulance moves toward you, the pitch or frequency sounds higher because the sound waves are closer together.

The Doppler Effect cont.

As the ambulance moves away from you the sounds waves are farther apart and the frequency or pitch is lower.

Multiple Choice

When a police car with the siren blasting is moving toward you, the pitch seem

• lower

• higher

• unchanged

End