Sound Flashcards
2 properties of sound waves:
- travel through air, water and other solids, liquids and gases
- cannot travel in a vacuum (they need molecules or atoms to pass on vibrations)
What is a longitudinal wave
One which the particles vibrate parallel to the direction of the wave motion
Compression - region of high pressure
Rarefaction - region of low pressure
Lowest to highest human hearing
20 Hz - 20 kHz
High frequency =
High pitch
High amplitude =
High volume
What is an ultrasound
Sound produced with a frequency above normal limit of human hearing
Used in pre - natal scanning and I’m industry in non - destructive testing
How is an electrical signal displayed
On an oscilloscope
How is Y-gain measured
In V/division
Vertical axis
How is timebase measured
s/division
Horizontal axis
How to find amplitude
Height of squares x y-gain
Number of divisions x y-gain setting
How to find time period?
One wave squares x time base
How to find frequency
1/time period
What 3 ways can you measure the speed of sound?
Simple timing
Using an echo
Electronic measurement
Using an echo:
Sound is made to echo from a large wall
When initial sound is heard, stop clock is started and when echo is heard, it’s stopped
Speed of sound = 2 x distance to wall / time taken between sound and echo
Electronic measurement :
Using a pc + suitable software, 2 mics can be connected which enable a sound to picked up and displayed
When sound passes the first mic, sound is registered and after the sound reaches the second mic
