science - reflecting and absorbing light Flashcards
what is a luminous object?
an object which can produce light by itself
what is a non-luminous object?
an object which cannot produce light by itselft therefor it reflects light.
what does reflect mean
to bounce off a surface
what does absorbing mean
when a material does not let light energy to pass through so instead it is absorbed by the material
how many colours is white light made up of
7
what are those colours
red, orange, yellow, green, blue, indigo and violet.
each colour has different frequencys. Which colour has the lowest frequency
red
Which colour has the greatest frequency
violet
true or false? Different filters will allow different colours to pass through.
true
true or false? if the colours do not pass through they will be absorbed
true
what does transparent mean
all light passes through
what does translucent mean
some light is blocked off
true or false? light travels in a straight line
true
what does opaque mean
no light passes through
true or false? the speed of light is 300,000 cm/s
false, The speed of light is 300,000 km/s
What does specular reflection mean
if the surface is smooth and flat then it will reflect in parallel rays and will produce a clear image
what does diffuse reflection mean
when it reflects off a rough, bumpy surface and produces a blurry image
what does the normal mean
an imaginary line at 90 degrees to the mirror
what does the incident ray mean
the ray of light that hits the surface of the mirror
what does the reflected ray mean
the ray that reflects off the mirror
what does the angle of incidence mean
angle between the incident ray and the normal
what does the angle of reflection mean
angle between the normal and the reflected ray
what is the material that a wave travels through called
a medium
what happens when light is absorbed
energy is transferred through the material
what is refraction?
when light passes through 2 different materials, it can change speed,
what is the law of reflection
angle of incidence is EQUAL to the angle of reflection
what does a convex lens look like
a piece of transparent material like glass or plastic that is thin around the edges but has a thick center. Looks like an oval/circle
what does a convex lens do?
it helps people if they are shortsighted by focusing light inwards
what is a concave lens/what does it look like
a piece of transparent material like glass or plastic that is thick around the edges but has a thing center. Looks like a rectangle however the long sides curve inwards to make sure that light is spread out
if an image is close, is the lens thick or thin
thick
if an image is far away, is the lens thick or thin?
thin
what does the cornea do?
controls and focus the entry of light into the eye
what does the iris do
regulates the amount of light that enters the eye
what does the pupil do
allows light to enter the eye so it can be focused on the retina
what does the lens do
absorbs, focuses and directs the light to the retina
what does the cillary muscle do
changes the shape of the lens
what does the retina do
senses light and sends signals to the brain
what does the optic nerve do
lets retina to send information to the brain
true or false? the shorter the focal length, the more powerful the lens is?
true
what is the focal length
distance between the center of a lens and its focus
what is the principle focus
the point on the principle axis of the lens at which an object is placed
