Quest #2 Flashcards
Converging lens
Convex
Diverging lens
Concave
Concave/diverging image always forms
Upright, virtual, smaller, same side as lens
Convex/converging on F
no image forms
Convex on 2F
On 2F, real, inverted, same size
Convex between 2F and F
Beyond 2F, real, inverted, larger
Convex beyond 2F
Between 2F and F, real, inverted, smaller
Convex between F and mirror
Same side as mirror, virtual, upright, larger
Refraction
The bending of light as it passes from one medium to another
Going from an object of lower density to higher density
bends away from the normal
Going from an object of higher density to lower density
bends away from the normal
The critical angle
The angle of incidence where the light refracts along the boundary between two mediums. Angle of refraction must equal 90
Total internal reflection
light reflects back into the first medium. Only occurs when light is travelling from a more optically dense to a less optically dense material + angle of incidence is greater than the critical angle
When the speed of light decreases, light bends
towards the normal
When the speed of light increases, light bends
away from the normal
Dispersion
Dispersion is the refraction fo white light into separate wavelengths of colours.
How does light go through the eye
Light enters through an opening, is focused through a lens, passes through a light-tight (dark) space, and forms a smaller, inverted, real image on a light-sensitive surface at the back.
cornea
the outer surface of the eye where light enters
pupil
a dark circular opening that allows light to pass into the eye
Iris
the coloured part of the eye. It is composed of circular band of muscles that regulate the size of the pupil (and the amount of light entering the eye
retina
The inner lining at the back of the eye that acts as a projection screen for the light rays entering the eye. The image on the retina is inverted, but the brain interprets it as being right side up
Ciliary Muscle
Can adjust the focal length by either contracting or relaxing
Blind spot
has no photoreceptors and can not detect light
where the optic nerve connects the eye to the brain
Hyperopia
You can see far but not close.
Causes: eyeball is too short, mage forms behind retina
How to correct it: converging (convex) lens
Myopia
You can see close but not far
causes: eyeball is too long, image forms in front of the retina
how to correct it: use a diverging (concave) lens
Astigmatism
a condition that causes blurry vision
causes: cornea is irregular shape(oval instead of round), light refracts irregularly
how to correct it: add a toroidal lens 2 focal points
presbyopia
Age related condition
Lens hardens and becomes less flexible
Ciliary muscles get weaker
Result: farsighted - can no longer see close
How can we correct their vision?
Add a converging lens
