The Medical College - Page 38
the lenses is approximately equal to the sum of
their focal
lengths. The eyepiece, in this design, can be
moved for-
ward or back in order to focus on the primates
as they
move closer to or further away from the
objective lens.
.
72.
The total tube length of the three sections is
to
be 4 m. The objective lens available has a
focal
length of 3 m. What should the focal length
of
the eyepiece lens be?
A.
0.75 m
C.
1.33 m
B.
1 m
D.
7 m
73.
A visitor seeing the sketch points out an
impor-
tant flaw that will require a design change.
What
is the flaw?
A.
The focal length of the eyepiece lens is
too
short.
B.
The images of the primates will be
inverted.
C.
The objective lens should be a
diverging
lens.
D.
The prisms cannot be used in this
way.
74.
What will be the approximate magnification
of
this periscope?
A.
0.67
C.
3
B.
1
D.
300
75.
The prisms (45-45-90° prisms) turn the
light
path through 90° by "total internal
reflection"
from the inside hypotenuse faces of the
prisms
when the incident angle is 45° as in the
sketch.
Can one use crown glass with an index of
refrac-
tion of 1.52 for the prism?
A.
Yes, because the critical angle for
crown
glass is 47°.
B.
Yes, because the critical angle for
crown
glass is 41°.
C.
No, because the critical angle for
crown
glass is exactly 47°.
D.
No, because the critical angle for
crown
glass is 41°.
Light Path
Objective Lens
Eyepiece
76.
Describe the properties of the image that
one
sees with this preliminary design.
A.
real, inverted, magnified
B.
real, upright, magnified
C.
virtual, upright, same size as
object
D.
virtual, inverted, magnified
77.
The telescope is focused on a primate rather
far
away on the far side of the large habitat. As
the
primate moves rather closer to the
telescope,
what must the observer do to see the
primate
clearly?
A.
No change, the image remains
clear.
B.
Move the eyepiece away from the
objec-
tive.
C.
Move the eyepiece closer to the
objective.
D.
Use an inverting eyepiece because
the
image flips.
Passage III (Questions 78–82)
A large vertical cylindrical tank of water
about 75 m
tall is used by the U.S. Navy to train
submariners in
techniques used to safely escape sunken
submarines in
shallow waters. The tanks are used for
physiological
experiments also. Until very recently all
submariners
had to undergo a yearly physical test to show
that they
could escape from a depth of several feet of
water
(without the use of any artificial breathing
apparatus).
The sailors enter an air lock and wait while
the air
pressure is increased until it equals the water
pressure
at the bottom of the tank. The bottom four feet
of the
air lock is filled with water. The door to the
tank is then
opened and the sailors take a final breath (of
the high
pressure air), swim out the door, and rise
slowly to the
surface. The trip to the surface takes several
minutes.
(During this time the swimmer exhales
continuously.)
The density of the water is 1000
kg/m
3.
78.
If the water is incompressible, what
pressure
does the water exert at the bottom of the 75
m
tall tank?
A.
3.6
10
5 N/m2
C.
72
10
5 N/m2
B.
7.35
10
5 N/m2 D.
75
10
5 N/m2
79.
One atmosphere of pressure (atm) =
1.01
10
5
N/m
2. Approximately how
many atmospheres
are exerted by the pressure at the bottom of
the
tank?
A.
72.0 atm
C.
7.3 atm
B.
8.36 atm
D.
0.836 atm
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