Light Flashcards
incident ray
a ray of light arriving at a surface
reflected ray
a ray of light which has been reflected from a surface
ray diagram
a diagram showing the path of rays of light
normal
line drawn at right angles to a surface at the point where a ray hits the surface
image
what we see when we view an object by means of reflected rays
in plain mirrors:
- always the same size
- same distance behind the mirror as the object is in front of it
- directly in line with the object
plane mirror
a mirror with a flat reflective surface
laterally inverted
an image in which left and right have been reversed
real image
an image that can be formed on a screen
virtual rays
rays that appear to be there but arent because theyre in the mirror
virtual image
an image that cannot be formed on a screen
when does total internal reflection occur?
When the incidence angle is larger than the critical angle
what is the angle of refraction when the incidence angle is equal to the critical angle?
90
critical angle
the angle of incidence which leads to the refraction of 90 degrees
total internal reflection
when light doesnt refract, only reflects
symbol with outgoing lines
convex, converging
symbol with ingoing lines
concave, diverging
object is placed more than 2f (converging)
image is smaller than object
object is at 2f (converging)
same size and distance
object is between 2f and f (converging)
the image gets larger
object is at f (converging)
no image is formed
object is between f and lens (converging)
virtual image is formed
refractive index formulas
n = sini/sinr
n = 1/sinc
relationship between angle of reflection and angle of incidence
the angle of incidence equals the angle of reflection
shape of converging/convex lens
leaf-like. Thicker at center.
(CONV = CONV)
shape of diverging/concave lens
hourglass. Thicker around the edges.
(conCAVE = cave opening-like)
Concave lens uses in terms of eye-sight
Is used to correct short-sightness - when the distance between the eye’s lens and retina is longer than it should be. Concave lens reduces the refraction of light and lengthens the focal length so that the image is formed on the retina.
Convex lens uses in terms of eye-sight
Is used to correct long-sightness - when the distance between the eye’s lens and retina is too short, as a result of which the focal point lies behind the retina. Convex lenses increase refraction and accordingly reduce the focal length.
How do convex/converging lens focus light?
Convex lens focuses light rays to a specific point
How do concave/diverging lens focus light?
concave lens diverges the light rays
use of optical fibres
long-distance and high performance data networking - telecommunication, such as internet, televison and telephones.
How do optical fibres work?
Light travels from one end to the other by total internal reflection.They can carry enormous amounts of information in light pulses trapped inside them.
use of optical fibres in medicine
endoscopy - to view internal organ part or for keyhole surgery
