Summer review - Waves Flashcards
How sound is made
Vibrations
Some sources of vibration
Vocal chords, speaker cone, violin strings
What part of the ear vibrates
Ear drum
How does sound travel from source to our ears
A connecting medium in the form of a longitudinal wave
What is a longitudinal wave
A wave where the vibrations are parallel to the flow of the sound energy
What happens to particles and air pressure when sound travels through air?
The air vibrates parallel to the source of flow of sound energy
Describe an experiment showing sound travels as a longitudinal wave
A speaker is next to a candle and played
The air in front of it is caused to vibrate
The candle flickers left and right in time with the speakers vibration
What is the bell jar experiment
A bell is placed inside a jar and rung
Air is removed making inside the jar a vacuum
The bell is no longer audible proving sound cannot travel through a vacuum
What are the relative speeds in a vacuum, a gas, a liquid and a solid of sound
Vacuum = 0m/s
Gas = 330m/s
Liquid = 1450m/s
Solid = 4000m/s
What is meant by ‘Mach 1’
Something travelling at Mach 1 is travelling at the speed of sound
How do you measure the speed of sound
Speed = distance/time
What happens when Mach 1 is exceeded
A sonic boom
How to create an audible echo
Make a noise far enough a way from a smooth surface
Far enough so it doesn’t merge with the original song and smooth so it comes back directly at you
How to measure the speed of sound using echoes
Make a sound, start timer, stop timer when echo is heard.
Speed = 2d/t
Give uses of echoes
Echo-location (bats,dolphins)
Sonar
Lunar laser ranging
What is the standard echo calculation
Speed = 2 x distance/time
What is reverberation
The merged noise of the sound and the echo when the echo time is less then 0.1s
What are the definitions of frequency and amplitude
Frequency - the number of vibrations per second
Amplitude - the maximum displacement of the vibrating medium from its equilibrium position
How is frequency related to pitch
The higher the frequency the higher the pitch
How is amplitude related to amplitude
The higher the amplitude the louder the sound
What is the range of human hearing
20Hz to 20kHz
How is Age related to the range of human hearing
The older you get the smaller your range of hearing
How does noise-induced hearing loss affect ability to hear sounds
The worse your noise-induced hearing loss the worse your range of hearing
How to interpret CRO wave forms
The height of the wave indicates the amplitude
The number of waves seen on the screen indicates the frequency
