JEE Main · 2026 · 06 Apr 2026 · Shift 1 · Wave Optics

An unpolarized light of intensity

I_{0}

passes through polarizer and then through a certain optically active solution and finally it goes to analyser. If the angle between analyser and polariser is

0^{\circ}

and intensity of light emerged from analyser is

\frac{3}{8} I_{0}

, the angle of rotation of the light by the solution with respect to analyser is

____

degrees.

Answer: 30

Solution

The polarizer transmits half the unpolarized light,

I^{'} = \frac{I _{0}}{2}

, and the active solution turns the plane of polarization by

θ

before the analyzer, which is parallel to the polarizer. By Malus's law

I = I^{'} cos^{2} θ = \frac{I _{0}}{2} cos^{2} θ = \frac{3 I _{0}}{8}

, so

cos^{2} θ = \frac{3}{4}

and

cos θ = \frac{3}{2}

. The rotation is

30

degrees.

JEE Main · 2026 · 06 Apr 2026 · Shift 1 · Integer answer

Practise more: all JEE Main PYQs on Wave Optics →

More JEE Main questions on Wave Optics

Given below are two statements:
Statement I: In a Young's double slit experiment, the angular separation of fringes will increase as the screen is moved away from the plane of the slits
Statement II : In a Young's double slit experiment, the angular separation of fringes will inc …
JEE Main 2026View solution →
In a Young's double slit experiment set up, the two slits are kept 0.4 mm apart and screen is placed at 1 m from slits. If a thin transparent sheet of thickness $20 μ m$ is introduced in front of one of the slits then centre bring fringe shifts by 20 mm on the screen …
JEE Main 2026View solution →
In two separate Young's double-slit experimental set-ups, two monochromatic light sources of different wavelengths are used to get fringes of equal width. The ratios of the slit separations and that of the wavelengths of light used are $2 : 1$ and $1 : 2$ respectively. The correspo …
JEE Main 2026View solution →
When an unpolarized light falls at a particular angle on a glass plate (placed in air), it is observed that the reflected beam is linearly polarized. The angle of refracted beam with respect to the normal is $____$ .
( $tan^{- 1} (1.52) = 57. 7^{\circ}$ , refractive indices of air a …
JEE Main 2026View solution →
Given below are two statements:

Statement-I: A plane wave after passing through prism remains as plane wave but passing through small pin hole may become spherical wave.
Statement-II: The curvature of a spherical wave emerging from a slit will increase for increasing slit width. …
JEE Main 2026View solution →
In the Young's double slit experiment the intensity produced by each one of the individual slits is $I_{0}$ . The distance between two slits is 2 mm. The distance of screen from slits is 10 m. The wavelength of light is $6000 \overset{˚}{A}$ . The intensity of light on the screen in front of …
JEE Main 2026View solution →