Chapter 13 Flashcards
Converging lens
Rays parallel to PA on side 1 go through the focal point on side 2
Rays that go through the v/PA intercept will continue along their path, the displacement is so small it can be ignored
Rays entering the lens through the focal point on side one will be parallel to the PA on side 2
Lens thick in middle and thin at edges
Diverging lens
Rays parallel to the PA on side one will diverge on side two as though it were coming from f1
As per usual, rays that go through the v/PA intercept will continue along their path, the displacement is so small it can be ignored
Rays on side one that are entering towards F2 will diverge so that the ray on side 2 is parallel to the PA
Lens is thin in middle and thick at edges
Lens terms
do = distance from object to optical centre
di = distance from image to optical centre
ho = height of object
hi = height of image
f = focal length of lens
M = magnification multiplier
F = focal point location(not in equations, just diagrams)
O = optical centre
Focal length (f) sign conventions
Positive means converging lens
Negative means diverging lens
distance (d) sign conventions
di is positive means real image
di is negative means virtual image
do is always positive
Height (h) sign conventions
hi is positive means upright image(therefore virtual)
hi is negative means inverted image(therefore real)
This is assuming ho is positive, otherwise reversed
Magnification(M) sign conventions
M is positive means image upright
M is negative means image inverted
Cornea
Outer protective layer
Where light enters the eye
Lens
Focuses light onto the retina
Biconvex
Pupil
Opening that allow light into the eye
Iris
Adjust pupil for more or less light
Optic nerve
Takes messages to brain
Retina
Made of rods and nerves that identify light
Hypernopia
Far sightedness
Difficulty seeing nearby objects
Problem is light focuses behind retina
Fixed by Positive meniscus
Modified converging lens
Myopia
Nearsightedness
Difficulty seeing distant images
Problem is light focuses in front of retina
Solution is negative meniscus
Modified diverging lens
