Waves - Glossary Flashcards
amplitude
the maximum displacement of a point of a wave from its rest position
frequency
the number of waves passing a point each second
longitudinal waves
waves that have vibrations along or parallel to their direction of travel e.g. sound waves
medium
substance through which waves can travel
transverse waves
disturbance caused by the wave is perpendicular to the wave’s direction, up and down as wave travels from left to right e.g. light wave
wavelength
distance covered by a full cycle of the wave, usually measured from peak to peak, or trough to trough
absorb
light waves are captured by an object, not reflected
angle
number of degrees
angle of incidence
angle between the incident ray and the normal
angle of reflection
angle between the reflected ray and the normal
converge
come together
convex
curving out or bulging outward
critical angle
angle of incidence that gives an angle of refraction of 90°
cyan
Light blue/turquoise colour
dispersion
splitting up of white light into the colours of the spectrum
diverge
spread out
electromagnetic wave
a wave that is both electric and magnetic in nature and that can travel through a vacuum, e.g., light waves, radio waves, microwaves
fibre optic
a glass or plastic “optical” fibre that carries light along its length
filter
an object that blocks some colours and lets others through
focal point
the point on the centreline of a lens or mirror at which reflected or refracted rays converge
focus
bringing together light to make a clear image; the region that can be seen clearly and where all objects appear to have sharp outlines
incident ray
light ray that hits a surface
inverted
upside down
kaleidoscope
the name given to a toy that uses several mirrors all facing inwards. The kaleidoscope produces many images of any object placed inside and this may give many new patterns
laser
concentrated beam of mono-coloured light
lens
(of eye) part of the eye that focuses light onto the retina; transparent glass or plastic that refracts light
light source
object able to generate its own light (luminous)
luminous
object that gives off light
magenta
pinky purple colour formed by mixing red and blue light; a secondary colour
magnify
cause objects to appear larger than they are
microscope
optical instrument for viewing small objects
mirror
polished or smooth surface that forms images by reflection
normal
imaginary line at right angles to where a light ray strikes a surface
opaque
a material that does not allow visible light to pass through it
periscope
an instrument for observation using mirrors (or prisms) that’s lets you see over walls or around corners
pinhole camera
very simple camera with no lens and a single very small hole
plane
mirror with a flat surface
primary (light) colour
one of three colours (red, blue and green) that combine to give all the other colours seen by the human eye
prism
triangular block of glass
ray diagram
diagram that shows which way light rays travel
real image
occurs when light rays actually pass through the point where the image is
reflect
bounce off a surface
reflected ray
light ray that bounces off the surface of a mirror or off water
refract
bend light as it passes through a transparent substance
refraction
change in the direction of a light ray as it enters a new medium
secondary (light) colour
light colours that can be made by mixing together primary colours; yellow, cyan and magenta
shadow
area of darkness where light is blocked by an object
spectrum
all the colours of the rainbow that make up sunlight (red, orange, yellow, green, blue, indigo, violet)
telescope (optical)
instrument designed for the observation of remote objects; uses mirrors and lenses
total internal reflection
occurs when light is completely trapped within a medium such as glass
translucent
a material that allow lights to pass through them but the light is scattered transmission
transparent
a material that allows visible light to pass through it without scattering
transmission
passing through. Heat, sound and light can be transmitted through some objects.
upright
right way up (opposite of inverted)
virtual image
occurs when light rays don’t pass through the point where the image is located
white light
formed from a mixture of different-coloured lights
aqueous humour
watery substance that is between the lens and the cornea
blind spot
point of the retina where the optic nerve leads into the brain that has no light-sensitive cells
camera
a device that takes photos of images
concave
curved inwards
cones
one kind of light-sensitive cell in the retina. Cones give you colour vision in bright light.
conjunctiva
clear membrane that covers the sclera (white part of the eye) and lines the inside of the eyelids
cornea
outer transparent surface of the eye
fovea
area of retina responsible for our central, sharpest vision
hypermetropia
far-sightedness or long-sightedness
iris
coloured muscular ring that controls the size of the pupil in a human eye
lens
a clear, flexible structure that makes an image on the eye’s retina
long sighted
a disorder of the eye which means that the muscles cannot pull the lens far enough for a person to be able to see short distances clearly.
myopia
near sighted
optic nerve
the bundle of nerve fibres that carry information from the retina to the brain.
pupil
the hole in the iris that allows light to enter the eyeball
retina
light sensitive surface at the back of the eye that converts light energy into electrical impulses
rods
one kind of light-sensitive cell in the retina. Rods respond in dim light.
sclera
the thick, tough, white outer covering of the eyeball.
short sighted
defect of eye where person sees nearby objects clearly but distant objects appear blurred; images focus in front of the retina
tapetum
the colourful, shiny material located behind the retina. Found in animals with good night vision, the tapetum reflects light back through the retina.
vitreous humour
the clear gel that fills the space between the lens and the retina of the eyeball
audible range
the range at which we can hear sound
decibel
the unit used to measure the intensity of a sound
echo
a reflection of sound, arriving at the listener some time after the direct sound
insulation
(sound) Materials used in buildings etc. To reduce the amount of sound transfer to and from the building
loudness
the greater the amplitude of a wave then the louder it is
pitch
same as frequency
sound wave
compressions and expansions of air created by a vibrating object
vacuum
no sound can be heard here because there are no air particles
vibration
movement of particles back and forth across a central position
auditory nerve
carries information between the cochlea and the brain
cochlea
coiled tube in the inner ear that converts sound energy into electrical impulses
ear drum
membrane divides the external ear from the middle ear.
Eustachian tube
a canal that links the middle ear with the back of the nose.
inner ear
oval window, cochlea and semi-circular canals
middle ear
ear drum, cavity and little bones
ossicles
tiny bones in the ear (hammer, anvil, stirrup)
outer ear
pinna and ear canal
pinna
ear flap (outer ear) directs sound into the inner ear
semi-circular canals
maintains balance when body is moving
