Waves Flashcards
What do waves transfer and not transfer?
Transfer: energy
Don’t transfer: matter
How are all waves produced?
Through vibrations.
What way do the vibrations move in a transverse wave?
Perpendicular to the direction in which the wave is travelling.
What way do the vibrations move in a longitudinal wave?
Parallel to the direction in which the wave is travelling.
What are the only two longitudinal waves?
Sound and ultrasound.
What is the wavelength of a wave? What is it usually measured in?
The distance between two consecutive crests or troughs. It is usually measured in metres, m.
What is the frequency of a wave? What is it usually measured in?
The numbers of waves that pass a point in one second. It is usually measured in Hertz, Hz.
What is the period of a wave? What is it usually measured in?
The time taken for one complete wave to pass a point. It is usually measured in seconds, s.
What is the amplitude of a wave? What is it usually measured in?
The MAXIMUM displacement of a wave from equilibrium position. It is usually measured in metres, m.
What is period related to? What is wavelength related to?
Period: time
Wavelength: distance
When the turns of a coil are close together what is it called?
A compression.
When the turns of a coil farthest apart what is the called?
Rarefaction
In terms of compressions and rarefactions, how do you find the wavelength of a longitudinal wave?
The distance between the centres of two consecutive compressions or rarefactions.
What is the wave equation?
Wave speed (v) = frequency (f) x wavelength (lambda)
What is the range of human hearing?
From 20 Hz to 20,000 Hz.
Sound at frequencies above 20 KHz cannot be heard and is called what?
Ultrasound.
What is the name given to a reflected sound?
An echo.
In terms of sound, what do hard surfaces do?
Reflect more sound and absorb less sound than softer surfaces.
What animals can produce ultrasound?
Whales, bats and dolphins.
Ultrasound has low wavelength, what does this mean?
They can be
-sent out in a very narrow beam
-focused on whatever is being investigated
What is the best-known example of the use of ultra sound?
Medical imaging.
Ultrasound is widely used in pre-natal scanning to check that the foetus is developing normally and to take measurements of its growth, but what measurements in particular?
The foetal head diameter.
Ultrasound can be also be used on other organs or soft tissues such as the heart, kidneys, blood vessels and bladder, but why would this be?
To diagnose cancers.
Aside from foetal head diameter checks and diagnosing cancers, what is another medical use of ultrasound?
The breaking down of kidney stones.
What is the main industrial use for ultrasound?
To detect cracks or flaws in metals.
Aside from detects defects in metals, what are some other industrial uses for ultrasound?
-Mapping the ocean floor in a field known as oceanography
-Cleaning sensitive electronic equipment
To detect layers of oil, coal, gas and other minerals deep underground.
How can ultrasound be used in dentistry?
-Diagnostics: can be used to create images of the teeth and surrounding tissues, gum disease, cavities etc
-Cleaning: Ultrasonic scalets use high frequency sound waves to remove plaque from teeth.
Why does a ship use ultrasound and not ordinary sound in this device?
-It is easier to concentrate ultrasound into a narrow beam
-Ultrasound can penetrate a greater depth of water
-Smaller objects can be located or scanned.
Who uses microwaves as radar waves for navigation?
Air traffic controllers, pilots and masters of large ships.
Why can only microwaves be used as radar waves for navigation, why can’t ultrasound waves?
As they do not travel fast enough. To track fast moving aircraft or more distant objects.
