Sound Flashcards
Are sound waves longitudinal or transverse?
Sound waves are propagated as longitudinal waves which travel in a direction parallel to the direction of the vibrations
Are sound waves mechanical or electromagnetic?
Sound waves require a medium to travel, so they are classified as mechanical waves
Describe how sound travels through air
When the vibrating object alternately pulls or pushes on the layers of air adjacent to it causes small but rapid changes in air pressure
When the layers of air are pushed closer together than normal, the air pressure begins higher than normal and a region of compression is formed
Where the layers of air are pulled further apart than normal, the air pressure becomes lower than normal, and a region of rarefaction is formed
What wave property affects the loudness of sound waves?
Loudness of sound waves increases as amplitude of the vibrations increases. Since increased loudness is caused by more vigorous vibrations, it is a measure of the amount of energy carried by the sound
What wave property determines the pitch of the sound?
Pitch of sound waves is determined by the number of waves formed in one second (its frequency)
What is the characteristic of sound that allows us to differentiate between 2 different sources of sound with the same pitch and loudness?
It is its quality, or timbre
Sounds which differ only in their quality…
Sounds which differ only in their quality will have different harmonics but same frequency and amplitude
they will have different shapes of wavefront, which can be displayed and observed on a cathode ray oscilloscope
Differences of speed of sound in various mediums
Speed of sound differs in gases, liquids and solids due to the differences in the strength of the interatomic forces, closeness of the molecules, and temperature.
Compression and rarefactions propagate faster in denser media
How is an echo produced?
When a sound wave is reflected by a large, hard and smooth surface, an echo is produced
What is the speed of sound in air?
300 m/s, 1000 000 times slower than the speed of light
What is the human audible frequency range?
20 to 20 000 hertz
What are ultrasonic and infrasound?
Ultrasonic frequencies are those above 20 000 Hz and infrasound are those below 20 Hz
How does ultrasound allow imaging?
Ultrasound allows imaging because of the difference in time taken for the waves to return from different depths of the medium
What is ultrasound used for?
It is used in medicine to examine internal tissue, organs and foetuses of patients
The computer constructs images of tissues/organs/foetuses from reflected ultrasonic signals
What are cathode ray oscilloscopes used for?
oscilloscopes are widely used for displaying waveforms. By selecting a suitable scale for the time base, we can display the voltage waveform by connecting to the Y-terminal input
