Physics Y10 Waves Flashcards
what is a transverse wave
a wave where the oscillations are perpendicular to the direction of travel
what is a longitudinal wave
a wave where the oscillations are parallel to the direction of travel
what are compressions
regions of high presure due to particles being close together
what are rarefractions
regions of low presure due to particles being far apart
do particles travel
no, they only move back and forth
does a wave travel
yes
what is the crest/peak
the highest point of a wave
what is the trough
the lowest point on a wave
what is the wavelength + units
the distance over which a wave’s shape repeats (metres, m)
what is frequency + units
amount of waves that pass a point per second (hertz, Hz)
what is the time period + units
time taken for one complete wave to pass a point (seconds, s)
relationship between frequency and time series
f = 1/T or T = 1/f
features of sound waves
- lonigtudinal
- require particles to propagate
- doesn’t travel in a vacuum
features of electromagnetic waves
- transverse
- do not require particles to propagate
- can travel in a vacuum
- all travel at same speed
- exist on a continuous spectrum of varying frequencies and wavelengths
features of water waves
- transverse
- require particles to propagate
calculate speed of a wave + units
wavelength * frequency (m/s)
what is ultrasound
sound waves that have frequencies above 20000Hz
what are the applications of ultrasound
- checking condition of foetus
- invetsigating heart / liver problems
- breaking down kidney stones / other stones
- measuring speed of blod flow in the body
how are medical images made using ultrasound
- ultrasound sent in
- some of the ultrasound gets reflected at boundaries between tissues or organs
- depth of each layer calculated using time taken for the wave to return
- processed to produce a picture on screen
what is an alternative to ultrasound + disadvantages
x-rays - high energy - could kil / damage human cells
why is ultrasound good
use low amplitude - safer for patient
how do you break kidney stones using ultrasound
high powered ultrasound wave vibrates to break down kidney stones
what is the epicentre of a seismic wave
the point on the surface at which the largest amount of energy is transferred
what is the focus of a seismic wave
the point at which the earthquake begins
features of primary waves
- longitudinal (push and pull)
- can travel through liquids
- 6km/s
how are radio waves produced
by moving electrons up and down in a broadcasting tower
features of secondary waves
- transverse
- cannot travel through liquids (e.g. earth’s core)
- 3.5km/s
what is visible light
the part of the electromagnetic spectrm which human eyes can detect
what do different frequencies mean in visible light
different colours
what are the colours in order of increasing frequency
red orange yellow green blue indigo violet
what happens when light refracts
- speed changes - towards normal = slower, away = faster
- changes direction
- wavelength changes
what are the different types of electromagneticwaves in order of increasing frequency
radio microwave infrared visible ultraviolet x-ray gamma
uses of radio waves
- broadcasting
- communications
- satellite transmissions
- reflect off of ionosphere
uses of microwaves
- cooking
- communications
- satellite transmissions
uses of infrared
- cooking
- thermal imaging
- short-range communications
- optical fibres
- TV remotes
- security systems
uses of visible light
- vision
- photography
- illumination
uses of ultraviolet
- security marking
- fluorescent lamps
- disinfecting water
uses of x-rays
- observe internal structures
- airport security cameras
- medical x-rays
uses of gamma rays
- sterilising food and medical equipment
- detection of cancer
- cancer treatment
