Refraction and Snell's Law

1
? / ?
ho/p ho/N
N p

M

q
?
N
? ? ho /N
?/? ho /p
2
Angular magnification
The closest image that you could clearly view
The farthest an image can be is?
3
A jeweler whose near point is 40 cm, examines a
diamond with a small magnifying glass. The lens
has a focal length of 5 cm and the image is -185
cm from the lens.

• Determine the angular magnification.
• b)Where should the image be located for
• viewing without eyestrain?
• What is the magnification then?
• c)What maximum magnification is possible?

Want q-? , so 1/q 0 ?
When q-N ?
4

Is the eye depicted above nearsighted or
farsighted? 1) nearsighted 2)
farsighted 3) could be either
5
An eyeglass prescription calls for lens powers of
2.1 D for the left eye and 2.5 D for the right
eye. The positive power means the lens is
converging. This person must be A)
nearsighted B) farsighted C) cannot tell
from information given
6
p 12 cm f1 8 cm
p2 40 cm q1 16 cm f2 12 cm
40 cm
Note overall M M1?M2 6
7
p 12 cm f1 8 cm
p2 32 cm 24 cm f2 12 cm
Move the lenses closer together so that the 1st
image is within the 2nds focal point.
32 cm
Note overall M M1?M2 -6
8
p 12 cm f1 8 cm
p2 16 cm 24 cm f2 12 cm
What if you move the lenses so close
together the 2nd interrupts the formation of
the 1st image?
16 cm
The object is virtual!
Note overall M M1?M2 -1.2
9
Is the eye depicted above nearsighted or
farsighted? A) nearsighted
As an object is moved closer to the eye, the
convergence point of the rays moves back (toward
the retina). So this eye can focus on objects
that are closer than the normal eye can focus.
B) farsighted
A positive lens power means the lens is convex,
or converging. So without the lens, the rays
must converge behind the retina, and so the
person is farsighted.