WORK SHEET-1
CHAPTER 9: WAVE OPTICS
SL. QUESTIONS ANSWER
NOMBER
1 Monochromatic light of wavelength 589 nm is incident from air
in a water surface. What are wavelengths frequency and speed
of (1) reflected light (2) refracted light? The refractive index of
water is 1.33
2 a) The refractive index of glass is 1.5. What is the speed of The speed of light in
light in glass? Speed of light in vacuum is 3.0 × 108 m glass depends on the
s−1) color of light.
b) Is the speed of light in glass independent of the colour
of light? If not, which of the two colours red and violet Since, the refractive
travels slower in a glass prism? index of the violet
color is greater than
red color, thus the
speed of the violet
light will be less than
red light in glass.
Therefore, the violet
component of white
light travels slower
than the red
component.(n=c/v)
3 Two coherent monochromatic light beams of 8/1
intensities I and 4I are superposed. The maximum and
minimum possible intensities in the resulting beam are:
4 (i) In diffraction due to a single slit, the phase A bright fringe occurs
difference between light waves reaching a when the phase
point on the screen is 5π. Explain whether a difference is an
bright or a dark fringe will be formed at the integer multiple
point. of 2π (i.e., 0,2π,4π,…).
(ii)
(ii)What should the width (a) of each slit be to A dark fringe occurs
obtain eight maxima of two double-slit patterns when the phase
(slit separation d) within the Central maximum difference is an odd
of the single slit pattern? multiple
of π (i.e., π,3π,5π,…).
A=d/4
5 In a double-slit arrangement the slits are separated by a a) .01rad
distance equal to 100 times the wavelength of the light passing b) .2cm
through the slits.
(a) What is the angular separation in radians between the
central maximum and an adjacent maximum?
(b) What is the distance between these maxima on a screen
50.0 cm from the slits?
6 In Young’s double-slit experiment using monochromatic light K/4
of wavelengthλ, the intensity of light at a point on the screen
where path difference is λ, is K units. What is the intensity of
light at a point where path difference is λ /3?
7 In a double slit experiment the angular width of a fringe is 0.150
found to be 0.2∘ on a screen 1 m away. The wavelength of light
used is 6000 Å. What will be the angular width of a fringe if the
entire experimental arrangement is immersed in water?
Refractive index of water =4/3.
8 In a double slit experiment using light of wavelength 600nm, if 3.44x10-4 m
angular fringe width is 0.1degree. find the separation between
2slits?
9 A parallel beam of light of wavelength 500 nm falls on a narrow
slit and the resulting diffraction pattern is observed on a screen
1 m away. It is observed that the first minimum is at a distance
of 2.5mm from the centre of the screen. Find the width of the
slit.
10 In the diffraction due to a single-slit experiment, the aperture Y= 7.8x10-4
of the slit is 3mm. If monochromatic light of wavelength 620
mm is incident normally on the slit, calculate the separation
between the first order minima and the 3rd order maxima on
one side of the screen. the distance between the slit and the
screen is 1.5 m
11 A beam of light consisting of two N=3
wavelength 800nmand600nm is used to obtain the interference
fringes in YDSE on a screen held 1.4m away. If the two slits are Y= 12x10-3 m
separated by 0.28mm, calculate the least distance from the
central bright maximum, where the bright fringes of the two
wave length coincide.
12 Two slits are one millimeter apart and the screen is placed one .2mm
meter away. What should the width of each slit be to obtain 10
maxima of the double slit pattern within the central maximum
of the single pattern.
13 Two wavelengths of sodium light 590 nm and 596 nm are used, 0.065mm
in turn, to study the diffraction taking place at a single slit of
aperture 2×10−4m. The distance between the slit and the screen
is 1.5 m. Calculate the separation between the positions of the
first maxima of the diffraction pattern obtained in the two
cases.
14 The intensity at the central maxima (O) in a Young's double slit
experiment is I0. If the distance OP equals one-third of the
fringe width of the pattern, show that the intensity at point P
would be I0/4.
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