Sound Waves Flashcards
what are sound waves
vibrations of air molecules
When a sound wave comes into contact with a solid those vibrations can be transferred to the solid
what are type of waves are sound waves and what does it consist of
Compressions - regions of higher density
Rarefactions - regions of lower density
what are the range of frequencies the human ear can hear
20 Hz to 20 000 Hz
how is sound waves transferred into ear
The pressure variations created by the sound wave exert a varying force on the eardrum causing it to vibrate
The vibration pattern of the sound waves creates the same pattern of vibration in the eardrum
eardrum vibration is transferred to the three small bones
The vibration of these small bones then transfers the vibrations to the cochlea and electrical impulses send a message to the brain giving the sensation of sound
what is ultrasound and the uses
Sound waves with a frequency above the human hearing range of 20 000 Hz
- foetal scanning and sonar to locate depth/distance
what is foetal scanning
ultrasound waves are passed through body when reach boundary between two medias some of the waves are reflected back and detected via electrical impulses to the scanner the timing and distribution of these echos are processed to produce video image
what is sonar scanning
Sonar uses ultrasound to detect objects underwater
The sound wave is reflected off the ocean bottom
The time it takes for the sound wave to return is used to calculate the depth of the water
what are infrasound waves used for
- animal communication as monitor infrasound to predict events
why are earthquakes significant
because they produce waves that have frequencies less than 20Hz so u can identify structure of earth
what are the two types of seismic waves
P-waves and S-waves
describe P-waves
longitudinal waves
travel through solids and liquids and faster than s-waves
describe s -waves
transverse waves and only pass through solids slower than p waves
what are the discoveries of seismic waves abt the mantle
The mantle is solid – this is because both types of wave can pass through it
what are the discoveries about the outer core using seismic waves
The outer core of the Earth is liquid – hence no S-waves can penetrate it
what discoveries about inner core
The inner core is solid – this is due to the size and positions of these shadow zones which indicate large refraction taking place
