Wave Optics Practice Questions - DPP for JEE

 Page 1


PART-I (Single Correct MCQs)
1. A YDSE is conducted in water (µ
1
) as shown in
figure. A glass plate of thickness  t and refractive
index µ
2
 is placed in the path of S
2
. The optical path
difference at O is
(a)
(b)
(c)
(d)
2. The condition for obtaining secondary maxima in the diffraction pattern
due to single slit is
(a)
(b)
(c)
Page 2


PART-I (Single Correct MCQs)
1. A YDSE is conducted in water (µ
1
) as shown in
figure. A glass plate of thickness  t and refractive
index µ
2
 is placed in the path of S
2
. The optical path
difference at O is
(a)
(b)
(c)
(d)
2. The condition for obtaining secondary maxima in the diffraction pattern
due to single slit is
(a)
(b)
(c)
(d)
3. Which of the following diagrams represent the variation of electric field
vector with time for a circularly polarised light ?
(a)
(b)
(c)
(d)
4. Two sources of light of wavelengths 2500 Å and 3500 Å are used in
Young’s double slit expt. simultaneously. Which orders of fringes of
two wavelength patterns coincide?
(a) 3rd order of 1st source and 5th of the 2nd
(b) 7th order of 1st and 5th order of 2nd
(c) 5th order of 1st and 3rd order of 2nd
(d) 5th order of 1st and 7th order of 2nd
5. The intensity at the maximum in a Young’s double slit experiment is I
0
.
Distance between two slits is d = 5l, where l is the wavelength of light
used in the experiment. What will be the intensity in front of one of the
slits on the screen placed at a distance D = 10 d ?
(a) I
0
(b)
(c)
Page 3


PART-I (Single Correct MCQs)
1. A YDSE is conducted in water (µ
1
) as shown in
figure. A glass plate of thickness  t and refractive
index µ
2
 is placed in the path of S
2
. The optical path
difference at O is
(a)
(b)
(c)
(d)
2. The condition for obtaining secondary maxima in the diffraction pattern
due to single slit is
(a)
(b)
(c)
(d)
3. Which of the following diagrams represent the variation of electric field
vector with time for a circularly polarised light ?
(a)
(b)
(c)
(d)
4. Two sources of light of wavelengths 2500 Å and 3500 Å are used in
Young’s double slit expt. simultaneously. Which orders of fringes of
two wavelength patterns coincide?
(a) 3rd order of 1st source and 5th of the 2nd
(b) 7th order of 1st and 5th order of 2nd
(c) 5th order of 1st and 3rd order of 2nd
(d) 5th order of 1st and 7th order of 2nd
5. The intensity at the maximum in a Young’s double slit experiment is I
0
.
Distance between two slits is d = 5l, where l is the wavelength of light
used in the experiment. What will be the intensity in front of one of the
slits on the screen placed at a distance D = 10 d ?
(a) I
0
(b)
(c)
(d)
6. In YSDE, both slits are covered by transparent
slab. Upper slit is covered by slab of R.I. 1.5 and
thickness t and lower is covered by R.I.  and
thickness 2t, then central maxima
(a) shifts in +ve y-axis direction               
(b) shifts in –ve y-axis direction 
(c) remains at same position
(d) may shift in upward
or downward depending upon wavelength of light
7. In a single slit diffraction experiment, the width of the slit is made
double its original width. Then the central maxima of the diffraction
pattern will become
(a) narrower and fainter
(b) narrower and brighter
(c) broader and fainter
(d) broader and brighter
8. A beam of light is incident on a glass slab (µ = 1.54) in a direction as
shown in the figure. The reflected light is analysed by a polaroid prism.
On rotating the polaroid, (tan 57° = 1.54)
(a) the intensity remains unchanged
(b) the intensity is reduced to zero and remains at zero
(c) the intensity gradually reduces to zero and then again increase
(d) the intensity increases continuously
9. Two identical light waves, propagating in the same direction, have a
phase difference d. After they superpose, the intensity of the resulting
wave will be proportional to
Page 4


PART-I (Single Correct MCQs)
1. A YDSE is conducted in water (µ
1
) as shown in
figure. A glass plate of thickness  t and refractive
index µ
2
 is placed in the path of S
2
. The optical path
difference at O is
(a)
(b)
(c)
(d)
2. The condition for obtaining secondary maxima in the diffraction pattern
due to single slit is
(a)
(b)
(c)
(d)
3. Which of the following diagrams represent the variation of electric field
vector with time for a circularly polarised light ?
(a)
(b)
(c)
(d)
4. Two sources of light of wavelengths 2500 Å and 3500 Å are used in
Young’s double slit expt. simultaneously. Which orders of fringes of
two wavelength patterns coincide?
(a) 3rd order of 1st source and 5th of the 2nd
(b) 7th order of 1st and 5th order of 2nd
(c) 5th order of 1st and 3rd order of 2nd
(d) 5th order of 1st and 7th order of 2nd
5. The intensity at the maximum in a Young’s double slit experiment is I
0
.
Distance between two slits is d = 5l, where l is the wavelength of light
used in the experiment. What will be the intensity in front of one of the
slits on the screen placed at a distance D = 10 d ?
(a) I
0
(b)
(c)
(d)
6. In YSDE, both slits are covered by transparent
slab. Upper slit is covered by slab of R.I. 1.5 and
thickness t and lower is covered by R.I.  and
thickness 2t, then central maxima
(a) shifts in +ve y-axis direction               
(b) shifts in –ve y-axis direction 
(c) remains at same position
(d) may shift in upward
or downward depending upon wavelength of light
7. In a single slit diffraction experiment, the width of the slit is made
double its original width. Then the central maxima of the diffraction
pattern will become
(a) narrower and fainter
(b) narrower and brighter
(c) broader and fainter
(d) broader and brighter
8. A beam of light is incident on a glass slab (µ = 1.54) in a direction as
shown in the figure. The reflected light is analysed by a polaroid prism.
On rotating the polaroid, (tan 57° = 1.54)
(a) the intensity remains unchanged
(b) the intensity is reduced to zero and remains at zero
(c) the intensity gradually reduces to zero and then again increase
(d) the intensity increases continuously
9. Two identical light waves, propagating in the same direction, have a
phase difference d. After they superpose, the intensity of the resulting
wave will be proportional to
(a) cos d
(b) cos (d/2)
(c) cos
2
 (d/2)
(d) cos
2
 d
10. In the Young’s double-slit experiment, the intensity of light at a point
on the screen where the path difference is ? is K, (? being the wave
length of light used). The intensity at a point where the path difference
is ?/4, will be:
(a) K
(b) K/4
(c) K/2
(d) Zero
11. In the phenomena of diffraction of light, when blue light is used in the
experiment in spite of red light, then
(a) fringes will become narrower
(b) fringes will become broader
(c) no change in fringe width
(d) None of these
12. Two coherent point sources S
1
 and S
2
 are
separated by a small distance d as shown.
The fringes obtained on the vertical
screen will be :
(a) points
(b) straight bands
(c) concentric circles
(d) semicircles
13. At the first minimum adjacent to the central maximum of a single-slit
diffraction pattern, the phase difference between the Huygen’s wavelet
from the edge of the slit and the wavelet from the midpoint of the slit is
:
(a)
(b) p radian
Page 5


PART-I (Single Correct MCQs)
1. A YDSE is conducted in water (µ
1
) as shown in
figure. A glass plate of thickness  t and refractive
index µ
2
 is placed in the path of S
2
. The optical path
difference at O is
(a)
(b)
(c)
(d)
2. The condition for obtaining secondary maxima in the diffraction pattern
due to single slit is
(a)
(b)
(c)
(d)
3. Which of the following diagrams represent the variation of electric field
vector with time for a circularly polarised light ?
(a)
(b)
(c)
(d)
4. Two sources of light of wavelengths 2500 Å and 3500 Å are used in
Young’s double slit expt. simultaneously. Which orders of fringes of
two wavelength patterns coincide?
(a) 3rd order of 1st source and 5th of the 2nd
(b) 7th order of 1st and 5th order of 2nd
(c) 5th order of 1st and 3rd order of 2nd
(d) 5th order of 1st and 7th order of 2nd
5. The intensity at the maximum in a Young’s double slit experiment is I
0
.
Distance between two slits is d = 5l, where l is the wavelength of light
used in the experiment. What will be the intensity in front of one of the
slits on the screen placed at a distance D = 10 d ?
(a) I
0
(b)
(c)
(d)
6. In YSDE, both slits are covered by transparent
slab. Upper slit is covered by slab of R.I. 1.5 and
thickness t and lower is covered by R.I.  and
thickness 2t, then central maxima
(a) shifts in +ve y-axis direction               
(b) shifts in –ve y-axis direction 
(c) remains at same position
(d) may shift in upward
or downward depending upon wavelength of light
7. In a single slit diffraction experiment, the width of the slit is made
double its original width. Then the central maxima of the diffraction
pattern will become
(a) narrower and fainter
(b) narrower and brighter
(c) broader and fainter
(d) broader and brighter
8. A beam of light is incident on a glass slab (µ = 1.54) in a direction as
shown in the figure. The reflected light is analysed by a polaroid prism.
On rotating the polaroid, (tan 57° = 1.54)
(a) the intensity remains unchanged
(b) the intensity is reduced to zero and remains at zero
(c) the intensity gradually reduces to zero and then again increase
(d) the intensity increases continuously
9. Two identical light waves, propagating in the same direction, have a
phase difference d. After they superpose, the intensity of the resulting
wave will be proportional to
(a) cos d
(b) cos (d/2)
(c) cos
2
 (d/2)
(d) cos
2
 d
10. In the Young’s double-slit experiment, the intensity of light at a point
on the screen where the path difference is ? is K, (? being the wave
length of light used). The intensity at a point where the path difference
is ?/4, will be:
(a) K
(b) K/4
(c) K/2
(d) Zero
11. In the phenomena of diffraction of light, when blue light is used in the
experiment in spite of red light, then
(a) fringes will become narrower
(b) fringes will become broader
(c) no change in fringe width
(d) None of these
12. Two coherent point sources S
1
 and S
2
 are
separated by a small distance d as shown.
The fringes obtained on the vertical
screen will be :
(a) points
(b) straight bands
(c) concentric circles
(d) semicircles
13. At the first minimum adjacent to the central maximum of a single-slit
diffraction pattern, the phase difference between the Huygen’s wavelet
from the edge of the slit and the wavelet from the midpoint of the slit is
:
(a)
(b) p radian
(c)
(d)
14. The adjacent figure shows Fraunhoffer’s diffraction due to a single slit.
If first minimum is obtained in the direction shown, then the path
difference between rays 1 and 3 is
(a) 0
(b) ? / 4
(c) ? / 2
(d) ?
15. If yellow light emitted by sodium lamp in Young’s double slit
experiment is replaced by a monochromatic blue  light of the same
intensity
(a) fringe width will decrease
(b) finge width will increase
(c) fringe width will remain unchanged
(d) fringes will become less intense
16. The Young’s double slit experiment is performed with blue and with
green light of wavelengths 4360Å and 5460Å respectively. If x is the
distance of 4th maxima from the central one, then
(a) x (blue) = x (green)
(b) x (blue) > x (green)
(c) x (blue) < x (green)
(d)
17. Two polaroids are placed in the path of unpolarized beam of intensity I
0
such that no light is emitted from the second polaroid. If a third