P12 Wave properties Flashcards
What can waves be used for?
To transfer energy and information
Give an example of a transverse wave
Water wave
Describe the shape of a transverse wave
The direction of the vibration of the particles is perpendicular to the direction in which the wave is travelling
Give an example of a longitudinal wave
Sound wave
Describe the shape of a longitudinal wave
The direction of the vibration of the particles is parallel to the direction in which the wave is travelling
What do mechanical waves travel through?
They travel through a medium
What are two examples of a mechanical wave?
Waves on springs and sound waves
What do electromagnetic waves travel through?
They can travel through a vacuum
What are two examples of a electromagnetic wave?
Light and radio waves
Are electromagnetic waves transverse or longitudinal?
Transverse
Are mechanical waves transverse or longitudinal?
Can be either
What is the amplitude of a wave?
The height of the wave crest from the midpoint of the wave
What is the wavelength of a wave?
Distance from one crest to the next crest
What is the frequency of a wave?
The number or wave crests that pass a point in one second
What is the period of a wave?
The time it takes for one wavelength to pass a point
What is the equation for the period of a wave?
Period of a wave = 1/frequency
What is the equation for wave speed?
Wave speed (m/s) = frequency (Hz) x wavelength (m)
What are incident waves?
Waves travelling towards a border or boundary
What is refraction?
When waves change speed or wavelength when they cross a boundary between different substances
Can sound waves travel through a vacuum?
No
Are sound waves longitudinal or transverse?
Longitudinal
How are echos produced?
When sound waves are reflected from a hard, flat surface
What is the range of human hearing?
20Hz to 20KHz
Why can humans not hear ultrasound waves?
Because they have a frequency of above 20KHz
Why are ultrasound waves safer than X-ray waves?
Because they are non ionising
How do ultrasounds work?
Ultrasound waves are partly reflected at a boundary between two different types of body tissue , these are timed and the timings are used to calculate distances
What are seismic waves?
Waves that travel through the earth
What are primary seismic waves (P-waves)?
They are longitudinal waves that cause the initial tremors, they refract at the boundary between the mantle and core
What are secondary seismic waves (S-waves)?
They are transverse waves that cause tremors after the first minute, they travel slower than P-waves and cannot travel through the liquid core of the earth
What are long waves (L-waves)?
They travel more slowly then P and S waves and only travel in the Earths crust. They arrive last and cause violent movement of the Earths crust
