Download Optics

AL-MC-Optics / p.1
1.
(88-I-21)
(1)
The first image is formed at the focal plane
of the objective.
(2)
The first image is real and inverted.
(3)
The focal length of the objective is longer
than that of the eyepiece.
A. (1), (2) and (3)
B. (1) and (2) only
C. (2) and (3) only
D. (1) only
When a pin is moved along the principal axis of a
E. (3) only
small concave mirror, the image position coincides
with the object at a point 0.5 m from the mirror. If
4.
(91-I-28)
the mirror is placed at a depth of 0.2 m in a
A simple two-convex lens refracting telescope has
transparent liquid, the same phenomenon occurs
a magnifying power of 12.5 when the telescope is
when the pin is placed 0.4 m from the mirror. The
in normal adjustment. The focal length of the
refractive index of the liquid is
objective is 0.75 m. The separation between the
objective and the eye piece is
2.
A.
6 / 5.
B.
5 / 4.
A.
0.06 m
C.
4 / 3.
B.
0.69 m
D.
3 / 2.
C.
0.81 m
E.
5 / 3.
D.
1.35 m
E.
16.7 m
(88-I-22)
A projector lens produces a clear, enlarged image
5.
(91-I-30)
of a slide on a screen. How could a clear image
The f-number of a certain camera is decreased
with greater magnification be obtained?
without changing any other camera controls. How
would the image size, image brightness and depth
screen movement
3.
lens movement
of field be affected?
A.
farther away
closer to the slide
Image
Image
Depth of
B.
farther away
none
size
brightness
field
C.
closer
away from the slide
D.
none
closer to the slide
E.
closer
closer to the slide
A.
decreased
decreased
increased
B.
decreased
increased
decreased
(90-I-20)
C.
increased
increased
decreased
In a simple astronomical telescope, under normal
D.
unaffected
increased
decreased
adjustment, which of the following statements
E.
unaffected
decreased
increased
is/are correct?
AL-MC-Optics / p.2
6.
(92-I-16)
8.
The image of an object formed on a screen by a
In an astronomical telescope set at normal
convex lens has height a. By moving the lens
adjustment, the focal lengths of the objective and
towards the screen, it is found that there is a
the eyepiece are 50 cm and 10 cm respectively.
second lens position at which another image of
Which of the following gives the separation of the
height b is formed on the screen. The height of the
lenses and the angular magnification of the
object is
telescope?
A.
( a  b) / 2
B.
a 2  b2
C.
ab
D.
a3 / b
E.
b3 / a
Lens separation
Angular
magnification
9.
7.
(92-I-18)
A.
30 cm
5
B.
40 cm
0.5
C.
40 cm
5
D.
60 cm
0.5
E.
60 cm
5
(92-I-19)
(92-I-17)
The sun subtends an angle of 0.5o at the surface of
the Earth. A convex lens of focal length 100 cm is
used to form an image of the sun onto a screen.
The diameter of the image is about
Light is incident on an octagonal mirror and
traverses a path ABCD, of total length L, before
A.
1 mm
being reflected again from another face of the
B.
3 mm
octagonal mirror. The octagonal mirror is rotated
C.
5 mm
and its angular velocity adjusted until the light
D.
9 mm
emerges in the same direction as when the mirror is
E.
50 mm
stationary. If the speed of light is c, the smallest
angular velocity to achieve this condition is
A.
B.
C.
D.
E.
 c/(8 L)
 c/(4L)
 c/(2L)
 c/L
2  c/L
AL-MC-Optics / p.3
10.
1
(Speed of light in air = 3  10 ms )
8
(93-I-21)
The f-numbers on the aperture ring of a camera are
as follows :
2
28.1o
32.2 o
41.8 o
48.0 o
57.8 o
A.
2.8
4
5.6
8
11
16
22
B.
Which of the following statements is/are true?
C.
D.
(1)
The camera’s largest aperture has an area of
f 2
16
(2)
where f is the focal length of the
E.
13.
(94-IIA-21)
Which of the following ray diagrams is/are correct?
camera lens.
(F is the focus of the corresponding optical
The depth of filed increases with increasing
instrument.)
f-number.
(3)
A photograph taken at f-number 5.6 and
exposure time
1
s receives the same
60
exposure as another taken at f-number 8 and
exposure time
11.
1
s.
120
A.
(1) only
B.
(3) only
C.
(1) and (2) only
A.
(1) only
D.
(2) and (3) only
B.
(3) only
E.
(1), (2) and (3)
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
14.
(95-IIA-13)
(93-I-23)
An object placed in front of a magnifying glass
forms an image at infinity with magnifying power
3. What is the focal length of the magnifying glass?
(You may assume the least distance of distinct
vision to be 25 cm)
When a beam of light travels from a medium X to
another medium Y, the variation in intensity of the
A.
12.
6.3 cm
B.
8.3 cm
C.
12.5 cm
D.
25 cm
E.
75 cm
refracted beam when angle
90 is as shown.
speed of light in X
What is the ratio
1:2
B.
1:3
C.
2:1
1.6  10 ms . Find the critical angle for that
D.
2:3
material and air.
E.
3:1
The speed of light in a certain material is
8
1
varies from 0
o
A.
(94-IIA-15)

speed of light in Y
o
to
AL-MC-Optics / p.4
15. (95-IIA-16)
A.
20 cm
An astronomical refracting telescope consists of
B.
30 cm
two converging lenses of focal lengths 100 cm and
C.
40 cm
5 cm. Under normal adjustment, it is used to
D.
50 cm
observe a distant object which subtends an angle of
E.
60 cm
0.2 o when viewed directly. Which of the
following statements is/are correct?
18. (96-IIA-19)
The image of the moon is focused on a screen by a
(1)
(2)
(3)
The lens with focal length 5 cm should be
converging lens of focal length 20 cm. If the moon
the objective.
The height of the first image formed by the
subtends an angle of 9.5  10 radian at the
centre of the lens, calculate the diameter of the
telescope is 3.5 mm.
image.
3
The angle subtended by the final image seen
by the observer is
4o .
A.
B.
A.
(1) only
C.
B.
(3) only
D.
C.
(1) and (2) only
E.
D.
(2) and (3) only
E.
(1), (2) and (3)
4.8  10 2 cm
9.5  10 2 cm
1.9  10 1 cm
3.8  10 1 cm
7.6  10 1 cm
19. (97-IIA-13)
A beam of monochromatic light passes through
16. (95-IIA-17)
When an object placed far away from a convex
lens is gradually moved towards the lens, the
separation between the object and its real image
will
17.
three media of refractive indexes
n1 , n 2 and
n3 respectively as shown. The boundaries
between the media are parallel.
A.
decrease.
B.
decrease and then increase.
C.
increase.
D.
increase and then decrease.
E.
remain unchanged.
(96-IIA-18)
A small object O is placed at the focus of a convex
lens L as shown. A concave mirror M is placed
80 cm behind the lens. If the focal length of L is
50 cm and the final image formed by this system is
at infinity, the focal length of M is
Which of the following relations between
n 2 and n3 is correct?
A.
n1 > n3 > n 2
B.
n3 > n1 > n 2
C.
n1 > n 2 > n3
D.
n 2 > n1 > n3
E.
n3 > n 2 > n1
n1 ,
AL-MC-Optics / p.5
20.
(97-IIA-18)
22.
(99-IIA-11)
An astronomical refracting telescope is adjusted to
view a distant object under normal adjustment.
Which of the following statements is/are correct?
(1) The first image formed by the objective is real
and is smaller than the object.
The above diagram shows two light rays from a
(2) The final image formed by the eyepiece is at
point source O passing in turn through a convex lens
the least distance of distinct vision from the
eye.
L1 and a concave lens L2 . Which of the following
(3) If part of the objective is blocked by an
is true of the focal lengths of the lenses.?
opaque obstacle, part of the final image could
not be viewed.
Focal length
of
21.
L1
Focal length
of
L2
A.
(1) only
B.
(3) only
A.
5 cm
less than 10 cm
C.
(1) and (2) only
B.
10 cm
less than 10 cm
D.
(2) and (3) only
C.
10 cm
10 cm
E.
(1), (2) and (3)
D.
5 cm
greater than 10 cm
E.
10 cm
greater than 10 cm
23.
(00-IIA-20)
(99-IIA-10)
In the above figure, XY is the principal axis of a
lens L. PQ and OS are two refracted rays from L
with originate from a point object placed on the
left side of L. Which of the following deductions
A converging light beam is directed towards a
is/are correct?
convex mirror M. The reflected beam then passes
through a convex lens L and forms an image at I.
(1)
The lens L must be a concave lens.
Which of the following about the focal lengths of
(2)
The point object must lie along the line OS.
M and L is correct?
(3)
The image of the point object must be
virtual.
focal length of M
focal length of L
A.
B.
C.
D.
more than 4 cm
less than 4 cm
4 cm
less than 4 cm
2cm
2 cm
2 cm
4 cm
E.
more than 4 cm
4 cm
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
AL-MC-Optics / p.6
24.
(01-IIA-16)
26.
(03-IIB-17)
The focal length of a concave mirror is f. The
In the following ray diagrams, L is a convex lens
mirror will produce a real, inverted and diminished
and F is one of its principal foci. Which of the ray
image when the distance of the object from the
diagrams is/are possible?
pole of the mirror is
A. greater than 2f
B. equal to 2f
C. between f and 2f
D. equal to f
E. less then f
25.
(02-IIB-16)
27.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
(03-IIB-20)
Typical microscopes and telescopes are both built
from two converging lenses. In which of the
following ways is a telescope similar to a
In the figure, L1 and L2 are two thin lenses with the
microscope when both are in normal adjustment?
same focal length 40 cm placed coaxially 20 cm
apart. A beam of light originating from a distant
A.
object is incident on L1. Which of the following
statements about the final image formed by the
is shorter than that of the eyepiece.
B.
system of lenses is correct?
It is real and formed on the right of L2
B.
It is real and formed between L1 and L2
C.
It is virtual and formed between L1 and L2
D.
It is virtual and formed on the left of L1
In each the separation of the lenses is equal
to the sum of their focal lengths.
C.
A.
In each the focal length of the objective lens
Each produces an intermediate image which
is linearly magnified and inverted.
D. In each the final image is inverted and virtual.
AL-MC-Optics / p.7
28.
(04-IIA-12)
In
the
figure,
P
and
Q
are
two
monochromatic light rays. One is red and
one is blue. They are parallel to the principle
axis of the glass lens L before being refracted
by the lens
Which of the following deductions are correct?
(1) P is the red light ray.
(2) L is a concave lens.
(3) Q travels faster than P in the lens
A.
(1) and (3)only
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1), (2) and (3)