Pavitra Gupta 9312281591
Pavitra Gupta 9312281591
WAVE OPTICS ( Numericals )
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The refractive index of the denser media is 1.732. Calculate:
(i) the polarising angle of medium.
(ii) the angle of refraction at the polarising angle.
[60°, 30°]
Determine the angular separation between central maximum and first order maximum of the diffraction
pattern due to a single slit of width 0.25 mm, when light of wavelength 5890 Å is incident on it normally.
[0.0035 radian]
In Young’s double slit experiment; the slits are separated by 0.24 mm. The screen is 1.2 m away from
the slit? The fringe width is 0.3 cm. Calculate the wavelength of light used in the experiment.
[6000 Å]
Two coherent sources whose intensity ratio is 81 : 1, produce interference fringes. Calculate the ratio of
(i) the amplitudes of light waves
(ii) intensity of maxima and minima in the fringe system.
[9:1, 100:64]
The two slits in Young’s double slit experiment are separated by a distance of 0.03 mm. An interference
pattern is produced on a screen 1.5 m away. The 4th bright fringe is at a distance of 1 cm from the central
maximum. Calculate the wavelength of light used.
[500 Å]
In Young’s double slit experiment, while using a source of light of wavelength 5000 Å, the fringe width
obtained is 0.6 cm. If the distance between the slits and the screen is reduced to half, calculate the new
fringe width.
[0.3 cm]
Laser light of wavelength 630 nm incident on a pair of slits produces an interference pattern in which the
bright fringes are separated by 8.1 mm. A second light produces an interference pattern in which the
fringes are separated by 7.2 mm. Calculate the wavelength of the second light.
[560 nm]
Consider interference between two sources of intensities I and 4I. Obtain intensity at a point where the
phase difference is /2.
[5 I]
In Young’s double slit experiment a light of 5000 Å is used. The third bright fringe is formed on the
screen at 1 cm from central bright band. If the screen is at a distance of 1.5 m from the center of the two
narrow slits, calculate the separation between the slits.
[0.225 x 10-3m]
A double slit is illuminated by light of  = 6000 Å. The slits are 0.1 cm apart and the screen is placed 1 m
away. Calculate: (a) angular position of 10th maxima in radian
(b) separation of two adjacent minima.
[0.006 radian, 0.6 mm]
The ratio of intensities of maxima and minima in an interference pattern is found to be 25 : 9. Calculate
the ratio of the intensities of the sources producing this pattern.
[Ans. 16: 1]
In Young’s double slit experiment; two slits are separated by 3 mm distance and illuminated by light of
wavelength 480 nm. The screen is at 2 m from the plane of the slits. Calculate the separation between the
8th bright fringe and the 3rd dark fringe observed with respect to the central bright fringe.
[1.76 x 10-3 m]
A ray of light falls on a transparent slab of refractive index 1.732. If reflected and refracted rays are
mutually perpendicular, what is the angle of incidence?
In a Young’s double slit interference experiment, the first minima on the screen is found just in front of
one of the slits when the slits are illuminated with a monochromatic source of wavelength 6000Å. If the
distance of the screen from the slits is 60 cm, calculate the separation between the slits.
In Young’s double-slit experiment using monochromatic light of wavelength λ, 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?
[K/4]
In a double-slit experiment the angular width of a fringe is found to be 0.2° on a screen placed 1 m away.
The wavelength of light used is 600 nm. What will be the angular width of the fringe if the entire
experimental apparatus is immersed in water? Take refractive index of water to be 4/3.
[0.15°]
In double-slit experiment using light of wavelength 600 nm, the angular width of a fringe formed on a
distant screen is 0.1º. What is the spacing between the two slits?
[3.4 × 10-4 m.]
Assume that light of wavelength 6000Å is coming from a star. What is the limit of resolution of a
telescope whose objective has a diameter of 100 inch?
[2.9 x 10-7 radian]
Pavitra Gupta 9312281591
Pavitra Gupta 9312281591