Home >> Topics >> Wave Optics
Unattempted Questions
Questions Available: 17
Year: 2018
Topic: Wave Optics
1.
Unpolarised light is incident from air on a plane surface of a material of refractive index ‘μ’. At a particular angle of incidence ‘i ’, it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation?
(1).
\(i=sin^{-1}\left(\frac{1}{\mu}\right)\)
(2).
Reflected light is polarised with its electric vector perpendicular to the plane of incidence
(3).
Reflected light is polarised with its electric vector parallel to the plane of incidence
(4).
\(i=tan^{-1}\left(\frac{1}{\mu}\right)\)

Year: 2017
Topic: Wave Optics
2.
The ratio of resolving powers of an optical microscope for two wavelengths \(\lambda_1 = 4000\,\mathring{A}\) and \(\lambda_2 = 6000\, \mathring{A}\) is
(1).
8 : 27
(2).
9 : 4
(3).
3 : 2
(4).
16 : 81

Year: 2025
Topic: Wave Optics
3.
The intensity of transmitted light when a polaroid sheet, placed between two crossed polaroids at \(22.5^\circ\) from the polarization axis of one of the polaroid, is (\(\text{I}_0\) is the intensity of polarised light after passing through the first polaroid):
(1).
\(\displaystyle \frac{\text{I}_0}{16}\)
(2).
\(\displaystyle \frac{\text{I}_0}{2}\)
(3).
\(\displaystyle \frac{\text{I}_0}{4}\)
(4).
\(\displaystyle \frac{\text{I}_0}{8}\)

Year: 2025
Topic: Wave Optics
4.
An unpolarized light beam travelling in air is incident on a medium of refractive index 1.73 at Brewster's angle. Then-
(1).
transmitted light is completely polarized with angle of refraction close to \(30^\circ\)
(2).
reflected light is completely polarized and the angle of reflection is close to \(60^\circ\)
(3).
reflected light is partially polarized and the angle of reflection is close to \(30^\circ\)
(4).
both reflected and transmitted light are perfectly polarized with angles of reflection and refraction close to \(60^\circ\) and \(30^\circ\), respectively.

Year: 2024
Topic: Wave Optics
5.
An unpolarised light beam strikes a glass surface at Brewster’s angle. Then
(1).
both the reflected and refracted light will be completely polarised
(2).
the reflected light will be completely polarised but the refracted light will be partially polarised (
(3).
the reflected light will be partially polarised
(4).
the refracted light will be completely polarised

Year: 2024
Topic: Wave Optics
6.
If the monochromatic source in Young's double slit experiment is replaced by white light, then
(1).
there will be a central bright white fringe surrounded by a few coloured fringes.
(2).
all bright fringes will be of equal width.
(3).
interference pattern will disappear.
(4).
there will be a central dark fringe surrounded by a few coloured fringes.

Year: 2022
Topic: Wave Optics
7.
In a Young’s double slit experiment, a student observes 8 fringes in a certain segment of screen when a monochromatic light of 600 nm wavelength is used. If the wavelength of light is changed to 400 nm, then the number of fringes he would observe in the same-region of the screen is :
(1).
6
(2).
8
(3).
9
(4).
12

Year: 2020
Topic: Wave Optics
8.
Assume that light of wavelength 600 nm is coming from a star. The limit of resolution of telescope whose objective has a diameter of 2 m is
(1).
\(1.83 \times 10^{-7}\) rad
(2).
\(7.32 \times 10^{-7}\) rad
(3).
\(6.00 \times 10^{-7}\) rad
(4).
\(3.66 \times 10^{-7}\) rad

Year: 2020
Topic: Wave Optics
9.
In Young's double slit experiment, if the separation between coherent sources is halved and the distance of the screen from the coherent sources is doubled, then the fringe width becomes
(1).
half
(2).
four times
(3).
one-fourth
(4).
double

Year: 2020
Topic: Wave Optics
10.
The Brewsters angle \(i_b\) for an interface should be
(1).
\(30^\circ\, <\, i_b\, <\, 45^\circ\)
(2).
\(45^\circ\, <\, i_b\, <\, 90^\circ\)
(3).
\( i_b\, =\, 90^\circ\)
(4).
\(0^\circ\, <\, i_b\, <\, 30^\circ\)

Year: 2019
Topic: Wave Optics
11.
In a double slit experiment, when light of wavelength 400 nm was used, the angular width of the first minima formed on a screen placed1m away, was found to be \(0.2^\circ\). What will be the angular width of the first minima, if the entire experimental apparatus is immersed in water? (μ water =4/3)
(1).
\( 0.15^\circ\)
(2).
\(0.051^\circ\)
(3).
\(0.1^\circ\)
(4).
\(0.266^\circ\)

Year: 2018
Topic: Wave Optics
12.
In Young’s double slit experiment, the separation "d" between the slits is 2 mm, the wavelength \(\lambda\) of the light used is 5896 Å and distance "D" between the screen and slits is 100 cm. It is found that the angular width of the fringes is 0.20°. To increase the fringe angular width to 0.21° (with same l and D) the separation between the slits needs to be changed to
(1).
2.1 mm
(2).
1.9 mm
(3).
1.8 mm
(4).
1.7 mm

Year: 2018
Topic: Wave Optics
13.
An astronomical refracting telescope will have large angular magnification and high angularresolution, when it has an objective lens of
(1).
large focal length and largediameter
(2).
large focal length and smalldiameter
(3).
small focal length and largediameter
(4).
small focal length and smalldiameter

Year: 2017
Topic: Wave Optics
14.
Young’s double slit experiment is first performed in air and then in a medium other than air. It is found that 8th bright fringe in the medium lies where 5th dark fringe lies in air. The refractive index of the medium is nearly
(1).
1.25
(2).
1.59
(3).
1.69
(4).
1.78

Year: 2017
Topic: Wave Optics
15.
Two polaroids \(\text{P}_1\) and \( \text{P}_ 2\) are placed with their axis perpendicular to each other. Unpolarised light \(\text{I}_0\) is incident on \(\text{P}_1\) . A third polaroid \(\text{P}_3\) is kept in between \(\text{P}_1\) and \(\text{P}_2\) such that its axis makes an angle 45° with that of \(\text{P}_1\). The intensity of transmitted light through \(\text{P}_2\) is
(1).
\(\displaystyle \frac{I_0}{2}\)
(2).
\(\displaystyle \frac{I_0}{4}\)
(3).
\(\displaystyle \frac{I_0}{8}\)
(4).
\(\displaystyle \frac{I_0}{16}\)

Year: 2016
Topic: Wave Optics
16.
The intensity at the maximum in a Young’s double slit experiment is \(I_0\). Distance between two slits is \(d\, =\, 5\lambda\), where \(\lambda\) 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?
(1).
\(\displaystyle \frac{I_0}{4}\)
(2).
\(\displaystyle \frac{3}{4}I_0\)
(3).
\(\displaystyle \frac{I_0}{2}\)
(4).
\(\displaystyle I_0\)

Year: 2016
Topic: Wave Optics
17.
In a diffraction pattern due to a single slit of width a, the first minimum is observed at an angle 30° when light of wavelength 5000 Å is incident on the slit. The first secondary maximum is observed at an angle of
(1).
\(\displaystyle sin^{-1}\left(\frac{2}{3}\right)\)
(2).
\(\displaystyle sin^{-1}\left(\frac{1}{2}\right)\)
(3).
\(\displaystyle sin^{-1}\left(\frac{3}{4}\right)\)
(4).
\(\displaystyle sin^{-1}\left(\frac{1}{4}\right)\)