cycle test 3 yr9 Flashcards
example of a longitudinal wave
sound
example of a transverse wave
light
what are the two main parts/features of a longitudinal wave
compressions and rarefactions
what are the two main parts/features of a transverse wave
troughs and crests
do longitudinal waves require a medium
yes, for vibrations to occur
do transverse waves require a medium
not required, can travel through vacumes
how is the energy transferred in a longitudinal wave?
the energy is transferred through vibrations in the direction of the wave (side to side)
how is the energy transferred in a transverse wave?
The energy is transferred vertically to the direction of the wave
amplitude in sound affects:
the volume
frequency in sound affects:
pitch
what is a period
The time it takes for two successive crests (one wavelength) to pass a point, or one full wave sycle
what is a wavelength
the distance between two identical points in a wave (eg. trough to trough)
what is an oscilloscope?
a device used to watch/study changing signals eg. sound waves and currents
what is period shown as and measured in
t, or time, measured in seconds
what is frequency
how many full cycles per second
what is frequency measured in
hertz (1 cycle = 1 hertz)
what is amplitude
the baseline (graph) to the crest of a wave
how to calculate frequency
1/period of time
how to calculate period
1/frequency
what is wave speed measured in
m/s
velocity is shown as
v
velocity is calculated by
frequency times wavelenth
if you decrease wavelength you
increase frequency
does increasing the frequency alter the wave speed?
no! instead the wavelength will decrease proportionally (inversely)
speed equals
distance over time
what is the speed of light
3 times 10 to the power of 8 m/s
is ultrasound higher or lower than a humans range of hearing?
higher
is infrasound higher or lower than a humans range of hearing?
lower
what is the range of human hearing
20-20000
what are some qualities of ultrasound waves
high f, low wavelength, converts electrical energy to sound for use in imaging
what kind of waves are x-rays
light waves, electro magnetic
why is it important to have high frequency and low wavelengths in ultrasound imaging
less diffraction, and therefore clearer images
what are some differences between ultrasound and x-rays
(don’t look)
ultrasound
reflects of tissues to produce images, can show soft tissue and fluid
sensors detect the reflection
produces a real time vid
safe, non ionising waves
x-rays
is blocked by pones (prevents light from affecting filter screen) so used for looking at bones
film detects light coming through (or lack of (white parts))
image is developed after
ionising radiation is created
how does an oscilloscope measure waves
it converts sound waves into electric signals that can be viewed on a screen
what spectrum are light waves on?
Electro-magnetic spectrum
what are some qualities of radio waves
low energy and danger
what are radio waves used for
communication (not as sound waves)
how large do radio waves have to be to be reflected by the ionosphere
10m (any smaller and they pass through)
How do microwaves interact with water and metals
they are absorbed by water and reflected by metals
how do microwaves interact with glass, paper and plastic?
they pass through
What is infrared emitted by
objects emitting heat energy/ reflecting it
what is ultraviolet light emitted by
the sun and other white hot objects
how does ultraviolet light interact with the environment?
it is absorbed by solids and passes through air
how does ultraviolet light affect humans
it increases melanin production, and can causes burns and cancer if overexposed
what are some properties of gamma radiation
extremely high frequency and short wavelengths, most penetrating and ionising radiation
what is gamma radiation emitted by?
radioactive substances
definition of refraction
change of a direction of light (causes dispersion and bending of light)
what is the iris?
the coloured part of the eye that controls the dilation and contraction of the pupil
what is the pupil
hole in the center of the eye where light passes through to reach the retina
what is the law of relfection
angle of incidence and reflection are equal
what are the two kinds of reflection
specular and diffuse
what does the lens do
it refracts light towards the retina
what is the retina
receptor cells that detect light and sends impulses to the brain via the optic nerve.
what is diffuse reflection
scattered reflections that produce an unclear image
specular reflection
clear and even image (produced with a mirror like/smooth material)
what is refraction
when a wave or light ray moves from one medium to another, causes a change in direction of light (due to speed changes)
what is the critical angle
an angle that defines the minimum point of total internal reflection
If the medium of refraction is less dense what happens to the light ray
it bends towards the normal
If the medium of refraction is more dense what happens to the light ray
the light ray bends away from the normal
the lower the amplitude:
the quieter the volume
the lower the frequency:
the lower the pitch
