CH10: General Wave Properties II: Sound Flashcards
how is sound produced?
they are produced by vibrating sources placed in a medium. the particles in the medium are set into vibration and energy is transferred from one particle to its neighbouring particles. a series of compressions and rarefactions are produced by vibrating particles.
what are compressions and rarefactions?
compressions: region where the medium’s density is higher than the surrounding density and pressure is higher than the surrounding pressure.
rarefactions: region where the medium’s density is lower than the surrounding density and pressure is lower than the surrounding pressure.
how is sound transmitted?
when sound is produced through a speaker, longitudinal waves are produced through the air with regions of compression and rarefactions, thereby transferring energy from one particle to the next particle, until it reaches the person who hears it.
speed of sound in water and air
air: 300 m/s
water: 1500 m/s
explain how the time taken differs when sound travels the same distance through air and through water?
sound takes a longer time to travel through air than in a=water. for sound to travel, part of the energy is transferred from one particle to another by collision. the particles in the air are far apart while the particles in water are closely packed.
define echo
a reflection of sound from a large, hard, flat surfaces
formula and SI unit of echo
v = 2d/t
SI unit: metre per second (m/s)
how are pitch and loudness related to sound waves?
pitch: related to the frequency of a sound wave. the higher the frequency, the higher the pitch.
loudness: related to the amplitude of a sound wave. the larger the amplitude, the louder the sound.
what is the range of frequencies that can be detected by the human ear? list some examples.
20 Hz to 20 kHz
infrasound to ultrasound
