waves and light Flashcards
what speed does light travel at
300 million m/s
why do you see lightning before you hear thunder
because light travels faster than sound
what is the law of reflection
the angle of incident = angle of reflection
what is the difference between the incident ray and the reflected ray
incident ray = the light shining directly from the light source
reflected ray= the light that bounces of a mirror
define dispersion
the separation of white light into colours or of any radiation according to wavelength
true or false.
light travels slower through solids than through gas
explain why
true : solids are more dense than air
what has the highest frequency:
a) red
b) cyan
c) yellow
d) violet
D (violet)
define a longitudinal wave
a wave in which the direction of the vibration is the same as the direction of sound
fill in the gaps
the particles in a L___________(a)_ wave move backwards and F_______(b)__ creating C___________(c)__ and R____________(d)__. rarefaction is the part of the wave where the particles are S_______(e)__ O____
a) longitudinal
b) forwards
c) compressions
d) rarefactions
e) spread / spaced out
what are the 3 secondary light colours
yellow, cyan and magenta [*remember the spelling of cyan]
julia shines a magenta torch on a red apple. what colour does the apple appear? why?
red- the apple absorbs the blue but reflects the red
julia shines a blue torch on a banana. what colour does it appear. why?
black- the blue light is absorbed so no light is reflected
julia shines a yellow light on a t-shirt. it has red sleeves, a cyan triangle in the middle and the rest is blue.
sleeves= red
triangle= green
the rest of it= black
define a wave
a disturbance that travels through a medium from one location to another, transferring energy
can waves travel through a vaccum
yes- thats how sunlight reaches earth
define amplitude
the distance between the rest position and the crest/ trough
define frequency
the number of complete waves per second
