Longitudinal Pulses And Waves Flashcards
What method is used to calculate the speed of sound in the air
The flash-and-bang method
Why can’t sound propagate through a vacuum
Sound is a longitudinal wave and needs a medium to travel through, because of this sound cannot travel through space
What happens when the compressions and rarefactions of a sound wave enter the ear
They are converted to electric impulses which are transmitted to the brain where it is interpreted as sound
The range of vibrations of sound the human ear can hear
A range from 20 Hz and 20 000 Hz (20 kHz)
How is the trace of a sound wave represented
Pressure variations on the y-axis
Time on x-axis
What is pitch
It is the effect produced in the ear due to the sound of a particular frequency
Pitch is directly proportional to frequency
Two notes of the same pitch and loudness, played on a different instrument do not sound the same why?
Because the waveforms are different and therefore differ in quality or tone
What’s a pure note
A single frequency
Sounds about 20kHz
Ultrasound
Ultrasound means beyond
20Khz to 100kHz
Uses of ultrasound in Medicine
Treatment of sports injuries - waves are fed through the skin to increase blood flow to the injured area
Imaging in pregnancy
How can an image be created with ultrasound
When an ultrasound wave encounters a boundary in a medium, part of the wave is reflected, the other part absorbed and the other part is transmitted through the boundary.
The reflected waves are detected in the same way as echoes and can be used to form an image
What’s an echo
A sound wave that is reflected of a surface
What are sound waves created by
By vibrations in a medium in the direction of propagation. The vibration causes a regular variation in pressure in the medium.
Properties of the medium that influence wave speed of sound
Density - sound travels faster in denser objects
Elasticity
Stiffness
Loudness of sound depends on
The amplitude of a sound wave
And the sensitivity of the human ear
Loudness is directly proportional to amplitude
