Wave Optics
Wave Optics
Wave Optics
3
(3) 2 × 108 m/s (4) 108 m/s
2
s1 s2
45. Light of wavelength is incident on a slit of width 2m
‘d’. The resulting diffraction pattern is observed on
a screen at a distance D. The linear width of the
principal maximum is then equal to the width of
the slit if D equals (1) 16 (2) 20
(3) 24 (4) 32
d 2
(1) (2)
d 3. Light wave travels in vacuum along the y-axis.
Which of the following may represent the
d2 2 2 wavefront?
(3) (4)
2 d (1) x = constant
46. In a Fraunhofer diffraction at a single slit of width (2) y = constant
d with incident light of wavelength 5500 Å, the first
minimum is observed at angle of 30°. The first (3) z = constant
secondary maximum is observed at an angle , (4) x + y + z = constant
equal to 4. In placing a thin sheet of mica of thickness
12 × 10–5 cm in the path of one of the interfering
1 1
(1) sin1 (2) sin1 beams in YDSE the central fringe shifts equal to
2 4 fringe width. Refractive index of mica ( = 600 nm)
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5. When an unpolarised light of intensity I0 is incident 10. In YDSE with identical slits, the intensity of the
on a polarising sheet, the intensity of the light central bright fringe is I 0. If one of the slits is
which does not get transmitted is covered, the intensity at the same point is
d2 1 5 1 4
(4)
4D (3) 4 (4) 5
2 2
8. The correct curve between fringe width and
distance between the slits (d) is 13. Consider a YDSE that has different slits widths. As
a result, amplitude of waves from two slits are A
and 2A, respectively. If I0 be the maximum intensity
of the interference pattern, then intensity of the
(1) (2) pattern at a point where phase difference between
wave is is
d d
I0
(1) I0 cos2 (2) sin2
3 2
(3) (4) I0 I0
(3) [5 4 cos ] (4) [5 8 cos ]
9 9
d d
14. Which of the following properties shows that light
9. Two coherent sources of light of wavelength is a transverse wave?
6.2 × 10 –6 m produce interference. The path.
difference corresponding to 10th order maximum (1) Reflection
will be (2) Interference
(1) 6.2 × 10–6 m (2) 3.1 × 10–6 m (3) Diffraction
(3) 1.5 × 10–6 m (4) 6.2 × 10–5 m (4) Polarisation
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NEET Wave Optics 37
15. The wavefront of a light wave travelling in vacuum 21. Two identical coherent sources are placed on a
is given by x + y + z = c. The angle made by the diameter of a circle of radius R at separation x(<<R)
direction of propagation of light with the x-axis is symmetrical about the centre of the circle. The
(1) 0° (2) 45° sources emit identical wavelength each. The
number of points on the circle of maximum
intensity is (x = 5)
1 1
(3) 90° (4) cos
3 (1) 20 (2) 22
(3) 24 (4) 26
16. If two sources of intensity I0 each have randomly
varying phase difference then the resultant 22. On introducing a transparent slab() the central
intensity will be given by fringe shift to the point originally occupied by the
fifth bright fringe. The thickness of the slab is
1 I0
(1) 2I (2) 5 4
0 2
(1) (2)
1 1
I0
(3) 2I0 (4)
2 1 1
(3) (4)
17. The angular width of the central maximum of the 4 5
diffraction pattern in a single slit (of width a) 23. Corpuscular theory of light predicts speed of light
experiment, with as the wavelength of light is to be
I0
(1) I0 (2)
2 L
I0 I0 L 1 (1 2 )L
(3) (4) (1) (2)
4 8 2 2
(1) x = a
(1) cos (2) cos
2 (2) y = a
(3) z = a
2
(3) cos (4) cos ( ) 2
2 (4) x + y + z = a
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26. Apparent wavelength of light coming from a star 32. Four different independent waves are represented by
moving away from earth is 0.02% more than its (i) y1 = a1sint (ii) y2 = a2sin2t
actual wavelength. Velocity of star is
(1) 30 km/s (2) 60 km/s (iii) y3 = a3cost (iv) y 4 a4 sin t
3
(3) 90 km/s (4) 120 km/s
With which of two waves interference is possible?
27. In Young double slit experiment, 12 fringes are
obtained in a certain fragment of the screen, when (1) (i) & (ii)
light of wavelength 600 nm is used. If the wavelength (2) (i) & (iv)
of light is changed to 400 nm, number of fringes (3) (iii) & (iv)
observed in the same segment of the screen is
(4) Not possible with any combination
(1) 12 (2) 18
33. In YDSE, a thin film (μ = 1.6) of thickness 0.01 mm
(3) 24 (4) 30 is introduced in the path of one of the two interfering
28. A thin film of water ( = 4/3) is 3100 Å thick. If it is beams. The central fringe moves to a position
illuminated by white light at normal incidence. The occupied by the 10th bright fringe earlier. The wave
colour of film in the reflected light will be length of wave is
y2 (4) 1 cm
(3) (4) All of these
4x 47. Slit widths in a Young’s double slit experiment are
in the ratio 9 : 4. Ratio of intensity at minima to
43. Shape of interference fringes formed on the screen
that at maxima is
due to point source P, in the case shown here
(1) 4 : 9
(2) 16 : 81
(3) 1 : 25
(4) 1 : 16
48. To observerve diffraction the size of an obstacle
(1) Should be of the same order as wavelength
(2) Should be much smaller than the wavelength
(3) Has no relation to wavelength
(1) Parabolic (2) Elliptical
(4) Should be exactly
(3) Circular (4) Hyperbolic 2
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40 Wave Optics NEET
49. In Fraunhoffer diffraction from a single slit, wave 54. Light of wavelength is coming from a star. What
front incident on the slit is is the limit of resolution of a telescope whose
(1) Planar objective has diameter r ?
(Q51 to Q55) - 3 3 2 3 1
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