chapter 11 lenses and the eye

Question 1

convex (converging) lens

Answer 1

-focuses parallel rays to a point called the principal focus
-forms virtual and real image

Question 2

concave (diverging) lens

Answer 2

-makes parallel rays spread out
-forms virtual image; upright, smaller than the object

Question 3

what type of image does a magnifying glass form

Answer 3

virtual image

Question 4

formation of virtual image by convex lens

Answer 4

upright, magnified and same side of the lens as the object

Question 5

formation of real image by convex lens

Answer 5

diminished, other side of the lens to the object, inverted

Question 6

the eye

Answer 6

light is focused onto the retina by the cornea and eye lens, whose shape is changed by the capilary muscle

Question 7

range of vision

Answer 7

25cm to infinity

Question 8

short sighted

Answer 8

-caused by eyeball being too long or eye lens being unable to focus sharp image onto the retina
-corrected by diverging (concave) lens
-eye cannot focus on distant objects
-image forms before retina

Question 9

long sighted

Answer 9

-caused by eyeball being too short, or eye being unable to focus sharp objects onto retina
-corrected by converging lens (convex)
-eye cannot focus on close objects
-image forms after retina

Question 10

in dark condintions

Answer 10

pupil dilate so iris expands to allow more light

Question 11

in bright condintions

Answer 11

pupil shrinks, so iris shrinks to allow less light

Question 12

looking at long distance

Answer 12

-cilary muscles relax, so the lens is thin to focus on far away objects

Question 13

looking at short distances

Answer 13

-cilary muscles contract, so lens is thick to look at close objects