Sound Flashcards
(15 cards)
What type of waves are sound waves
Longitudinal waves
What happens to waves after being reflected?
Amplitude decreases.
Everything else stays the same.
What happens to waves after being refracted from deep to shallow?
Wavelength decreases.
Frequency is same.
Velocity decreases.
How are sound waves generated?
By any object that vibrates.
E.g. the vibrating prongs of a tuning fork or vibrating vocal cords.
It is passed on through vibrating particles.
What are the regions in longitudinal waves where molecules become bunched together?
Compressions, distance between one compression and another is one wavelength
What is the name of the regions where the molecules are spread out?
Rarefactions
What does the bell in the jar experiment tell us?
Sound cannot travel though a vacuum but light can
How can sound not travel through a vacuum?
For sound waves to transfer energy, material molecules are required to pass on the vibrations.
Before the vacuum pump was on there were air molecules in the jar and in this case of the vibrating gong, air molecules were forced to start vibrating.
These molecules then bumped into neighbouring molecules and caused them to vibrate and like a chain reaction molecules between the gong and our ear passed on the vibrations.
When the air had been sucked out there are no air molecules left to vibrate and therefore cannot transfer the vibrations of the gong.
What would you see on a C.R.O (Cathode Ray Oscilloscope) if you struck a tuning fork hard?
Large amplitude
What if a short tuning fork was used in a C.R.O?
Higher pitched sound.
Higher frequency.
What is ultrasound?
Frequencies above 20000 Hz or 20 kHz.
Human hearing range is 20 Hz to 20000 Hz.
Listening to loud sounds for prolonged periods may damage your hearing and cause progressive deafness.
Uses of ultrasound
Dog whistle
Cataract surgery
Sonar - to locate shoals of fish, submarines or estimate the depth of the seabed
Measurement of blood flow
Echo-cardiology
Scans are used to check the development of unborn babies.
Last four are ultrasound echoes.
What advantage do ultrasound scans have over X-rays when scanning internal organs or an unborn foetus?
Non ionising - not likely to harm foetus or person
What is an echo?
The reflection of a sound wave from a large, flat hard surface.
Hard surfaces reflect sound waves while soft surfaces absorb sound.
What is the equation for speed in an echo?
Speed = 2 times the distance divided by time
