3 4 sound

Sound waves are produced by vibrating (or oscillating) sources.

The region of a sound wave that contains a lower density of particles is called a rarefaction.

False. Sound waves are longitudinal waves.

True. Sound waves are longitudinal waves so they do require a medium to travel through.

The region of a sound wave that contains a higher density of particles is called a compression.

Compressions are regions with a high density of particles, while rarefactions are regions with a low density of particles.

True. Sound is a type of pressure wave consisting of compressions and rarefactions, which cause changes in pressure that vary with the wave.

False. Sound waves require a medium to travel through, so they cannot travel through a vacuum where there are no particles.

When sound waves hit a solid, the variations in pressure cause the surface of the solid to vibrate in sync with the sound wave.

The speed of sound is the speed which sound travels through a particular medium.

The speed of sound in air at room temperature is about 340 m/s.

True. The speed of sound in air varies from 330 – 350 m/s, with higher temperatures leading to a greater speed of sound.

Sound travels fastest in solids because the particles in a solid are closer together.

Sound travels the slowest in gases because the particles are furthest apart.

True. Measuring the speed of sound using an oscilloscope is the most accurate method because the timing is done automatically.

Sounds with a high frequency (or short wavelength) have a high pitch, and sounds with a low frequency (or long wavelength) have a low pitch.

Sounds with a large amplitude have a high volume, and sounds with a small amplitude have a low volume.

False. Decreasing the amplitude of a sound wave will decrease its volume.

False. Increasing the frequency of a sound wave will increase its pitch.

Decreasing the frequency of a sound wave will decrease the pitch of the sound.

Increasing the amplitude of a soundwave would increase the volume of the sound.

The range of human hearing is 20 to 20 000 Hz.

Ultrasound is the name given to sound waves with a frequency greater than 20,000 Hz.

True. Ultrasound is not audible to humans because it has a frequency greater than 20,000 Hz, which is beyond the range of human hearing.

When ultrasound reaches a boundary between two media, some of the waves are partially reflected, while the remainder are transmitted through the material.

Humans can hear sounds between about 20 Hz and 20,000 Hz in frequency, although this range decreases with age.

Ultrasound transducers emit ultrasound and receive ultrasound.

The time taken for ultrasound reflections to reach a detector can be used to determine how far away a boundary is, as ultrasound travels at different speeds through different media. This allows ultrasound waves to be used for both medical and industrial imaging.

False. Unlike many other medical imaging techniques, ultrasound is non-invasive and is believed to be harmless.

True. In industry, ultrasound can be used to check for cracks inside metal objects and generate images beneath surfaces.

True. Ultrasound can be used as a medical treatment, such as removing kidney stones.

Yes. Humans can detect sounds with frequencies in the range of 20 Hz to 20 kHz.