module 5 (waves and light) Flashcards
define penumbra
where the light is partially blocked
define umbra
the centre where it appears dark (fully blocked)
define shadows
when light is blocked by an opaque object
define the rule of reflection
when light rays are reflected from a surface, the angle of incidence is equal to the angle of reflection
define an incident ray
a ray of light that is pointing towards and striking a surface
define reflection
when light bounces off an object
define refraction
the bending of light or sound as it passes through something
when does refraction occur?
when it has suddenly become more difficult or easy for waves to move and they suddenly change speed
what happens when light rays enter a dense subject?
the light rays are refracted towards the normal
what happens when light rays return to a lower density material?
the light rays are refracted away from the normal
define light dispersion
the separation of white light into colours of any radiation according to wave length
define white light
light made up of all the colours on the visible spectrum
what are the primary colours in light?
red, green, blue
what are the secondary colours in light?
magenta, yellow, cyan
define a wave
a transfer of energy form one place to another
define a medium
a substance that can carry the wave
define a transverse wave
a wave where the medium moves up and down, perpendicular to the direction of energy transfer
define a longitude wave
a wave where the medium moves back and forth, parallel to the direction of energy transfer
define amplitude
the distance from the centre line to the top of the crest or to the bottom of the trough
define wavelength
the distance on one point of one wave to the same point on the next wave
define compression
a region where the particles are closest together
define rarefraction
a region where the particles are further apart
define frequency
how many waves occur each second
what is frequency measured in?
Hertz (Hz)
define period
the time it takes for one wave to pass (in seconds)
