AL-MC-Superposition / p.1
1.
(88-I-23)
3.
(89-I-21)
The coated lens of a camera appears purple in
daylight. According to the manufacturers, the
coating has a refractive index of 1.25 and the
When monochromatic light is incident normally on
material of the lens has a refractive index of 1.50.
a wedge-shaped thin air film, an interference
If the wavelength of yellow light in air is 520 nm,
pattern may be seen by reflection. Which of the
the approximate thickness of the coating is
following is/are correct?
A.
104 nm.
(1)
Parallel fringes are observed.
B.
130 nm.
(2)
If water is introduced into the region
C.
180 nm.
between the plates, the fringe separation
D.
210 nm.
decreases.
E.
260 nm.
(3)
If the angle of the wedge is increased, the
fringe separation decreases.
4.
(89-I-22)
Light of wavelength

is incident normally on a
A.
(1), (2) and (3)
diffraction grating with p lines per millimetre. The
B.
(1) and (2) only
second-order diffraction maximum is at an angle
C.
(2) and (3) only

D.
(1) only
with 3p lines per millimetre illuminated normally
E.
(3) only
by light of wavelength 5  /4, the angle between
from the central position. For a second grating
the first-order diffraction maximum and the central
2.
position is
(88-I-24)
 . Which of the following relations is
correct?
A.
Polarized light is obtained by passing a narrow
B.
beam of unpolarized light from source S through a
C.
tank of water to which a drop of milk has been
D.
added. Which of the following statements is/are
E.
correct?
(1)
Light from source S must be monochromatic.
(2)
Completely polarized light is detected at
position M.
(3)
The drop of milk provides particles to scatter
the light.
A.
(1), (2) and (3)
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1) only
E.
(3) only
sin 
sin 
sin 
sin 
sin 
= (5 sin  ) / 12
= sin( 5 / 12)
= sin( 15 / 4)
= (15 sin  ) / 8
= sin( 15 / 8)
AL-MC-Superposition / p.2
5.
(90-I-25)
7.
(91-I-20)
When parallel light is incident at the Brewster
Orange light of wavelength 600 nm (in air) is
angle in air on the surface of a glass block, which
incident normally from air onto a liquid film whose
of the following statements is/are correct?
refractive index is 1.25. For what minimum value
of film thickness will the greatest amount of light
(1)
The refracted light is plane-polarised.
be transmitted through the film?
(2)
The reflected light is plane-ploarised.
(3)
The reflected ray and the refracted ray are at
A.
120 nm
right angles to each other.
B.
180 nm
C.
240 nm
A. (1), (2) and (3)
D.
300 nm
B. (1) and (2) only
E.
480 nm
C. (2) and (3) only
D. (1) only
8.
E. (3) only
(91-I-21)
In experiments with optical diffraction gratings, the
grating spacing
6.
(90-I-26)
wavelength of light
White light diffracted by a single slit falls on a
is of the order of
white screen. Which of the following statements
is/are correct?
A.
(1)
The centre of the diffraction pattern is white.
B.
C.
(2)
The first minimum is closer to the center for
D.
red light than for blue light.
E.
(3)
10 6
10 3
1
10 3
10 6
The central band width is increased as the slit
width is increased.
9.
(91-I-22)
In an arrangement for viewing Newton’s rings, if
A. (1), (2) and (3)
the lens which rests on a glass plate were moved
B. (1) and (2) only
slowly upwards by one wavelength (of the viewing
C. (2) and (3) only
light), which of the following would be observed?
D. (1) only
E. (3) only
A.
The central spot becomes bright.
B.
The rings disappear.
C.
The rings move towards the centre.
D.
The rings move out from the centre.
E.
The rings are no longer concentric.
AL-MC-Superposition / p.3
10.
(91-I-23)
12.
(92-I-24)
When unpolarised light travelling in air falls on the
surface of a glass block, it is possible to find an
angle of incidence such that
A.
none of the light is reflected.
B.
the reflected light and the transmitted
Light from an unpolarised source is allowed to fall
light are both plane polarised.
on a piece of polaroid P and then on a second
C.
all the light is reflected.
polaroid A. In the position shown in the diagram,
D.
the transmitted light is plane polarised.
the intensity of the light emerging from polaroid A
E.
the reflected light is plane polarised.
is a maximum. As A is slowly rotated, the intensity
of light emerging is reduced to half the maximum
value at angle
1
and to a minimum at angle
13.
(92-I-25)
2 .
Which of the following gives the correct values of
angles
1
and
A light source S is viewed through two parallel
2 ?
pieces of polaroid P and Q. Q is gradually rotated
until the field of view becomes dark. Which of the
A.
B.
C.
D.
E.
1
2
following conclusions can be drawn?
30 o
45 o
45 o
60 o
60 o
90 o
90 o
180 o
90 o
180 o
(1)
The experiment shows that light is a
transverse wave.
(2)
The experiment shows that light from source
S must be unpolarised.
(3)
When Q is rotated further by 90o, the field of
view becomes dark again.
11.
(91-I-24)
When a diffraction grating is replaced by another
A.
(1), (2) and (3)
with more lines per mm, which of the following
B.
(1) and (2) only
quantities is/are increased?
C.
(2) and (3) only
D.
(1) only
E.
(3) only
(1)
the angle of diffraction for every spectral line
(2)
the angular separation of red and blue lines
in the first order spectrum
(3)
the number of orders which can be observed
A. (1), (2) and (3)
B. (1) and (2) only
C. (2) and (3) only
D. (1) only
E. (3) only
AL-MC-Superposition / p.4
14.
(92-I-26)
17. (95-IIA-14)
In Young’s double-slit experiment, which of the
following combinations of monochromatic light,
the slit-separation and the slit-to –screen distance
would produce the widest fringe separation on the
screen?
A ray AO of monochromatic light wavelength

Monochromatic
Slit-
Slit-to
light
separation
screen
falls on a thin parallel-sided soap film of thickness
distance
t and refractive index n. Constructive interference
will take place between rays M and N when
A.
nt = m 
B.
nt = (m + 1/2)
C.
2 nt = m 
D.
2 nt

A.
red light
1mm
1m
B.
red light
1mm
2m
C.
red light
2mm
1m
D.
green light
1mm
2m
E.
green light
cos r = m 
2 nt cos r = (m + 1/2) 
E.
(m is an interger)
2mm
1m
18. (95-IIA-15)
A coating material of refractive index 1.25 is used
15.
(93-I-22)
for the blooming of a lens having a larger
Which of the following equations correctly gives
refractive index. For normal incidence, if green
the relation between the polarising angle i and the
light is to be transmitted in its greatest amount
refractive index n of a material?
through the lens, which of the following
thicknesses of the coating would do? (Given :
sin i  n
n sin i  1
cos i  n
n tan i  1
tan i  n
A.
B.
C.
D.
E.
16.
wavelength of green light in air is 550 nm)
(1)
137.5 nm
(2)
220 nm
(3)
330 nm
(94-IIA-17)
A.
(1) only
Which of the following waves can be polarised?
B.
(3) only
C.
(1) and (2) only
(1)
microwaves
D.
(2) and (3) only
(2)
X-rays
E.
(1), (2) and (3)
(3)
ultrasonic waves
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
AL-MC-Superposition / p.5
19. (96-IIA-13)
21.
(96-IIA-15)
When a beam of unpolarized light travelling in air
falls on a water surface, it is possible to find an
angle of incidence such that
(1)
all the light is reflected.
(2)
the light passing into water is plane
A beam of white light is shone normally on a
polarized.
diffraction grating. The diagram shows the spectra
the reflected light is plane polarized.
of the first two orders, which may not be drawn to
(3)
scale. The first-order spectrum starts at an angle of
20.
A.
(1) only
20 o from the zeroth order. The respective angular
B.
(3) only
separations between the two ends (red and violet) of
C.
(1) and (2) only
a spectrum are  and  for the first- and second-
D.
(2) and (3) only
order spectra. Which of the following statements
E.
(1) and (3) only
is/are correct?
(96-IIA-14)
(1)
In the first-order spectrum, P is the violet
end.
(2)
 is greater than  .
(3)
There is no third-order spectrum.
Monochromatic light of wavelength 589 nm is shone
normally on a wedge-shaped thin air film to form
A.
(1) only
interference fringes. If the distance between the sixth
B.
(3) only
and ninety-sixth dark fringes is 15.8 mm, calculate
C.
(1) and (2) only

D.
(2) and (3) only
E.
(1), (2) and (3)
the angle of the wedge,
A.
B.
C.
D.
E.
.
o
0.024
0.048 o
0.072 o
0.096 o
0.190 o
22. (96-IIA-20)
3-cm microwaves are used in a radar speed trap.
When the emitted and reflected signals are
superposed, beats are produced. Find the minimum
beat frequency above which a driver would be
prosecuted for exceeding a speed limit of
100 km h-1.
A.
1000 Hz
B.
1900 Hz
C.
2400 Hz
D.
3400 Hz
E.
4700 Hz
AL-MC-Superposition / p.6
23.
(97-IIA-15)
25. (97-IIA-19)
A plane transmission grating is placed at the centre
of a circular 0  360 protractor. A beam of
monochromatic light is incident normally on the
o
o
grating. The zeroth-order maximum occurs at a
In a Young’s double-slit experiment, light of
scale reading of 90
wavelength 400 nm is used. If the path difference
between the light from the two slits X and Y to a
occurs at scale reading of 65 . At what scale
reading would a second-order maximum be
point P on the screen is 3000 nm, which of the
observed?
o
and a first-order maximum
o
following is/are correct?
A.
(1)
P is the 7th dark fringe.
B.
(2)
The fringe separation on the screen increases
C.
if the light source is moved closer to the slits.
D.
P becomes a bright fringe if light of
E.
(3)
148 o
140 o
130 o
58 o
40 o
wavelength 500 nm is used.
26. (98-IIA-12)
A.
(1) only
A beam of red (R) light and violet (V) light strikes
B.
(3) only
normally on a diffraction grating. Several orders of
C.
(1) and (2) only
diffraction of the light beam are produced on each
D.
(2) and (3) only
side of central axis. The wavelength of the red light
E.
(1), (2) and (3)
is 700 nm and that of the violet light is 400 nm. How
will the second- and third- order diffracted beams of
24. (97-IIA-17)
both colours appear? (The central axis is marked
In an arrangement for viewing Newton’s rings,
with a dot and the diffracted beams of other orders
which of the following would be observed if water
are not shown.)
is introduced to the space between the lens and the
glass plate?
Central axis
A.
The rings disappear.
B.
The central spot becomes bright.
C.
The separation between the rings
A.

The rings shift towards the centre.
E.
There is no observable change.
R V
R
|
|
|
V
B.

increases.
D.
V
C.
D.
E.



|
V
R
R
|
|
|
|
V
R
R
V
|
|
|
|
R
R
|
|
R
V
|
|
V
|
|
R
|
V
V
|
AL-MC-Superposition / p.7
27. (98-IIA-15)
29.
(00-IIA-19)
Sunlight is scattered by air molecules in the
atmosphere. Which of the following statements
concerning this process is/are correct?
(1)
(2)
(3)
Light is absorbed by air molecules and is
then re-emitted.
A glass lens is made non-reflecting for yellow light
The scattered light observed on the earth’s
by coating it with a thin film of transparent
Surface is partially plane-polarized.
material of a refractive index less than that of glass.
Red light is scattered more than blue light is.
Which of the following statements is/are correct?
A.
(1) only
(1)
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
The surface of the glass lens appears yellow
in white light.
(2)
The minimum thickness of the film is 1/4 of
the wavelength of yellow light in the film.
(3)
As a result of the destructive interference
between the light rays reflected from the two
28.
(99-IIA-12)
interfaces, energy which would have been
In a Young’s double slit experiment, a
wasted as reflected light increases the
monochromatic light source of wavelength 700 nm
amount of transmitted light.
is used and the separation of the slits is 0.1 mm. If
15 bright fringes are observed, what is the angle
A.
(1) only
subtended by those fringes at the center of the
B.
(3) only
double slit?
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
30.
(01-IIA-12)
In which of the following cases can the principle of
superposition be applied to two overlapping waves
of the same nature?
A.
4.8 
A. Only when the two waves have the same
B.
5.2 
frequency.
B. Only when the two waves have the same
C.
5.6 
amplitude.
C. Only when the two waves travel in
D.
6.0 
opposite directions.
D. Only when the two waves are coherent.
E.
6.4 
E. It can be applied in all cases.
AL-MC-Superposition / p.8
31.
(01-IIA-13)
33.
(01-IIA-17)
A student prepares a double-slit set-up as shown
Three polaroid sheets P, Q and R are placed along a
below. However, no interference fringe can be
straight line with a lamp and a detector as shown.
observed on the screen.
Initially the directions of polarization of P and Q
are parallel but are both normal to that of R. What
Your suggestion for improvement may be
happens to the intensity I recorded by the detector
when Q is being rotated slowly through 90° until
A. using a mercury lamp to provide radiation
its direction of polarization is parallel to that of R?
of a shorter wavelength.
B. reducing x.
A. I remains unchanged
C. reducing D.
B. I increases throughout
D. increasing a.
C. I decreases throughout
E. reducing d.
D. I increases and then decreases
E. I decreases and then increases
32.
(01-IIA-14)
Which of the following statements concerning
Newton’s rings is/are correct?
34.
(02-IIB-14)
In which of the following the phenomenon of
polarization cannot be observed?
(1)
(2)
(3)
A convex lens with long focal length should
be used.
A.
Light reflected from the surface of water
Adjacent rings become farther apart when
B.
Microwaves emitted from a transmitter
moving outwards from the central spot.
C.
Light scattered from a clear sky
The central spot is bright when some liquid
D.
Ultrasonic waves used in sonar.
is introduced between the convex lens and
the reflector.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
AL-MC-Superposition / p.9
35
(02-IIB-15)
When a certain monochromatic light is passed
through a diffraction grating, a pattern of maxima
and minima is observed as shown. Which of the
following combinations would produce the largest
angle between the first-order maxima?
Grating (lines per mm) Colour of light used
36.
A.
200
blue
B.
200
red
C.
400
blue
D.
400
red
(04-IIA-11)
A Young’s double slit experiment was performed
using a monochromatic light source. Which of the
following methods would result in a greater fringe
separation on the screen?
(1) Using a monochromatic light source of longer
wavelength
(2) Using a double slit with greater slit separation
(3) Using a double slit with larger slit width
A.
(1) only
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1), (2) and (3)