Lenses and the eye Flashcards
concave lens
diverging lens:
forms virtual image-
upright, smaller than the object, same side of the lens as the object
convex lens
converging lens:
forms real image-
diminished, image is formed on the other side of the lens to the object, inverted
forms virtual image-
upright, magnified, same side of the lens as the object
hyperopia
long sightedness- cannot focus of nearby objects
image formed behind retina
eye ball is too short or lens is too weak/thin
corrected by converging (convex) lens
myopia
short sightedness- cannot focus on far away objects
image formed before retina
eye ball is too long or lens is too thick/powerful
corrected by diverging (concave) lens
in bright condintions
pupil shirnks, iris shrink to allow less light in
in dark condintions
pupils dilates, iris expands to allow more light in
looking at long distance
ciliary muscles relaxes so the lens is thin
looking at short distances
ciliary muslces contracts, so the lens is thick
what happens when object is moved closer to F, inverted image
-image distance increase
-image size increases
what happens when the object is moved past F,nearer to the lens than the focal point, inverted image
-image distance decreases
-image size decreases
how is a converging lens used to produce a sharp images on the film when the object is a long distance away from the camera, and is close to the camera
-move lens with respect to film
-closer for distanct objects
-further for near objects
describe how the image formed by the lens in a camera is differet to a lens used in magnifying glass
in camera image is real. inverted and diminished
eye compared to digital camera
-refracts light to produce image:
eye, cornea and lens
camera, lens
-image are focused here:
eye, retina
camera, CCD
-Variable opening where light enters:
eye, pupil
camera, aperture
what lens does a camera use
convex
what lens does a magnifying glass use
concave
