Waves Flashcards
2 types of waves
transverse and longitudinal
transverse waves
waves that vibrate or oscillate perpendicular to the direction of energy transfer
where can transverse waves move
- in solids and on the surface of liquids
what do transverse waves transfer
energy
which types of waves can move in solids, liquids and gases in a vacuum
electromagnetic waves
the highest point above the rest position in a T wave
peak/crest
lowest point below the rest position in a T wave
trough
examples of transverse waves
- EM waves
- S waves
- vibrations in a guitar string
longitudinal waves
where the points along its length vibrate parallel to the direction of energy transfer
where can longitudinal waves move
solids, liquids and gases
where can longitudinal waves not move
in a vacuum
when the waves are close together in L waves they are called
compressions
when waves are spaced apart in longitudinal waves they are called
rarefactions
examples of longitudinal waves
- sound waves
- Pressure waves
- P waves
pressure in T waves
constant
pressure in L waves
changes in pressure
when are L waves the fastest
solid
when are T waves the fastest
vacuum
waves
oscillations or vibrations about a fixed point
what do waves transfer
energy
what do waves not transfer
matter
amplitude
distance from the undisturbed position to the peak or trough of a wave
what is amplitude easured in
metres (m)
wavelength
distance from one point on the wave to the same point on the next wave
how is wavelength measured in L waves
from the centre of one compression to the centre of the next
wavelength symbol
lamba (wave)
frequency
the number of waves passing a point in a second
what is symbol and measurement of frequency
f
Hertz (Hz)
time period
the time taken for a single wave to pass a point
time period measurement
seconds (s)
Frequency equation
f= 1/T
Wave equation
wave speed= frequency x wavelength
doppler effect
the apparent change in wavelength and frequency of a wave emitted by a moving source
doppler effect in ambulance
- frequency of the sound waves emitted by the siren goes from high to low pitch
waves on a stationary object
spread out symmetrically
what happens to the waves when an object begins to move
waves get squashed together at one end and streched on the other end
electromagnetic waves
transverse waves that transfer energy from the source of the waves to an observer
properties of EM waves
- all transverse
- all travel through a vacuum
- they all travel at the same speed in a vacuum
what do EM waves form
continuos spectrum
EM waves
radio
microwaves
infrared
visible light
ultraviolet
x-rays
gamma rays
the higher the frequency=
the higher the radiation
radiation with higher energy is =
highly ionising
harmful to cells and tissues causing cancer
visible light
range of wavelengths which are visible to humans
visible light percentage of the EM spectrum
0.0035%
which color has the longest wavelength and lowest frequency
red
which colour has the shortest wavelength and highest frequency
violet
what is inversely proportional to wavelength
frequency
radio waves uses
communication (radio and TV)
microwave uses
heating food
communication (WIFI, mobiles, satellites)
infrared uses
- heating or cooking
- motion sensors
- remote controls
- electric heaters
- infrared cameras
visible light uses
- seeing and taking photographs
- fibre optic communications
ultraviolet uses
- security marking
- fluorescent bulbs
- getting a suntan
x ray uses
- x ray images
gamma rays
- sterilizing medical instruments
- treating cancer
microwaves danger
possible heat damage to internal organs
infrared danger
skin burns
visible light danger
bright light can cause eye damage
UV light danger
eye damage
sun burn
skin cancer
x rays and gamma rays danger
kills cells
mutations
cancer
