light and optics quiz 2 Flashcards
what is refraction
the bending or change of direction when light travels from one medium into another
index of reflection symbol
n
speed of light in a medium
v
equation of speed of light in a vacuum
3.0 x 10/8 m/s
Critical angle
the angle of incidence that results in an angle of refraction of 90 degrees
Total internal reflection
when the angle of incidence is greater that the critical angle
what 2 conditions must be meet before total internal refection can be occur
- light travels slower in the first medium than the second
- angle of incidence is large enough that no refection occurs in the medium, the ray is reflected back into the first medium instead
biconvex (converging) lens
the ovel shape, light rays converge
biconcave (diverging)
vase shape- light rays spreed apart
F’
secondary primary focus
beyond 2F’ (biconvex - converging)
s: smaller
a: inverted
l: between f &2f
t: real
At F’ (biconvex - converging)
s: same size
a: invented
l: at 2F
t: real
Between 2F’ and F’ (biconvex - converging)
s: larger
a: inverted
l: Beyond F
t: real
At F’(biconvex - converging)
NO IMAGE
Inside F’ (biconvex - converging)
s: much larger
a: up-right
l: same side lens as object
t: virtual
in diverging lens, in image is always….
s: smaller
a: upright
l: same side lens as object
t: virtural
Accommodation
the change of shape of the eye lens by eye muscles to allow a sharply focused image o the retina
Myopia
nearsighted (see close thing)
difficulty seeing FAR
image form in front of retina
corrected wit diverging lens
Hyperopia
Farsighted
difficulty seeing NEAR things
images forms behind rentina
corrected with converging lens
Presbyopia
a type of farsightedness caused by the loss of accommodation
occurs as a person ages
photoreciptor cells
rod & cone cells
rod cells
sensitive to light - used to see black and white
cannot provide a clear image due to the large amount of the cells
cone cells
allow seeing colour - not sensitive - work weel in bright conditions
fewer cells to see detailed colour
diaphragm (camera vs human eye)
Iris
- controls amount of light entering