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). \(i=tan^{-1}\left(\frac{1}{\mu}\right)\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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). \(\displaystyle \frac{\text{I}_0}{8}\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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.

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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.

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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). \(0^\circ\, <\, i_b\, <\, 30^\circ\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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). \(0.266^\circ\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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). \(\displaystyle \frac{I_0}{16}\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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). \(\displaystyle I_0\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

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). \(\displaystyle sin^{-1}\left(\frac{1}{4}\right)\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02