Question

In a Young's double slit experiment,$16$ fringes are observed in a certain segment of the screen when light of wavelength $700 \mathrm{nm}$ is used. If the wavelength of light is changed to $400 \mathrm{nm}$, the number of fringes observed in the same segment of the screen would be :

JEE Main 2020 (02 Sep Shift 2)

Options

• A: $24$
• B: $30$
• C: $18$
• D: $28$

Question

A beam of plane polarized light of large cross-sectional area and uniform intensity of $3.3 \mathrm{W} {\mathrm{m}}^{–2}$ falls normally on a polarizer (cross-sectional area $3\times {10}^{–4} {\mathrm{m}}^2$), which rotates about its axis with an angular speed of $31.4 \mathrm{rad} {\mathrm{s}}^{-1}$. The energy of light passing through the polarizer per revolution, is close to:

JEE Main 2020 (04 Sep Shift 1)

Options

• A: $1.0\times {10}^{-5} \mathrm{J}$
• B: $1.0\times {10}^{-4} \mathrm{J}$
• C: $1.5\times {10}^{-4} \mathrm{J}$
• D: $5.0\times {10}^{-4} \mathrm{J}$

Question

In the figure below, $P$ and $Q$ are two equally intense coherent sources emitting radiation of wavelength $20\mathrm{m}.$ The separation between $\mathrm{P}$ and $\mathrm{Q}$ is $5\mathrm{m}$ and the phase of $\mathrm{P}$ is ahead of that of $\mathrm{Q}$ by $90°.\mathrm{A},\mathrm{B}$ and C are three distinct point of observation, each equidistant from the midpoint of PQ. The intensities of radiation at $\mathrm{A},\mathrm{B},\mathrm{C}$ will be in the ratio :

JEE Main 2020 (06 Sep Shift 1)

Options

• A: $0:1:4$
• B: $2:1:0$
• C: $0:1:2$
• D: $4:1:0$

Question

The aperture diameter of a telescope is $5\mathrm{m}$ . The separation between the moon and the earth is $4\times {10}^5\mathrm{}\mathrm{k}\mathrm{m}$ . With light of wavelength of $5500\mathrm{}\mathrm{\AA }$ , the minimum separation between objects on the surface of moon, so that they are just resolved, is close to:

JEE Main 2020 (09 Jan Shift 1)

Options

• A: $60\mathrm{m}$
• B: $20\mathrm{m}$
• C: $200\mathrm{m}$
• D: $600\mathrm{m}$

Question

A beam of plane polarized light of large cross-sectional area and uniform intensity of $3.3 \mathrm{W} {\mathrm{m}}^{–2}$ falls normally on a polarizer (cross-sectional area $3\times {10}^{–4} {\mathrm{m}}^2$), which rotates about its axis with an angular speed of $31.4 \mathrm{rad} {\mathrm{s}}^{-1}$. The energy of light passing through the polarizer per revolution, is close to:

JEE Main 2020 (04 Sep Shift 1)

Options

• A: $1.0\times {10}^{-5} \mathrm{J}$
• B: $1.0\times {10}^{-4} \mathrm{J}$
• C: $1.5\times {10}^{-4} \mathrm{J}$
• D: $5.0\times {10}^{-4} \mathrm{J}$

Question

In a Young's double slit experiment $15$ fringes are observed on a small portion of the screen when light of wavelength $500 \mathrm{n}\mathrm{m}$ is used. Ten fringes are observed on the same section of the screen when another light source of wavelength $\lambda$ is used. Then the value of $\lambda$ is (in $\mathrm{n}\mathrm{m}$ ) __________.

JEE Main 2020 (09 Jan Shift 2)

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Question

In the Young's double slit experiment, the distance between the slits varies in time as $d\left(t\right)=d_0+a_0 \sin \omega t$; where $d_0, \omega$ and $a_0$ are constants. The difference between the largest fringe width and the smallest fringe width obtained over time is given as:

JEE Main 2021 (25 Jul Shift 1)

Options

• A: $\frac{2\lambda D\left(d_0\right)}{\left(d_0^2-a_0^2\right)}$
• B: $\frac{2\lambda D{a}_0}{\left({ d}_0^2-a_0^2\right)}$
• C: $\frac{\lambda D}{d_0^2}{a}_0$
• D: $\frac{\lambda D}{d_0+a_0}$

Question

An unpolarized light beam is incident on the polarizer of a polarization experiment and the intensity of light beam emerging from the analyzer is measured as $100$ Lumens. Now, if the analyzer is rotated around the horizontal axis (direction of light) by $30°$ in clockwise direction, the intensity of emerging light will be _______Lumens.

JEE Main 2021 (24 Feb Shift 1)

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Question

Two coherent sources of light interfere. The intensity ratio of two sources is $1:4$. For this interference pattern if the value of $\frac{I_{\max }+I_{\min }}{I_{\max }-I_{\min }}$ is equal to $\frac{2\alpha +1}{\beta +3}$, then $\frac{\alpha }{\beta }$ will be

JEE Main 2022 (27 Jul Shift 2)

Options

• A: $1.5$
• B: $2$
• C: $0.5$
• D: $1$

Question

Sodium light of wavelengths $650 \mathrm{nm}$ and $655 \mathrm{nm}$ is used to study diffraction at a single slit of aperture $0.5 \mathrm{mm}$. The distance between the slit and the screen is $2.0 \mathrm{m}$. The separation between the positions of the first maxima of diffraction pattern obtained in the two cases is _____ $\times {10}^{-5} \mathrm{m}$

JEE Main 2022 (24 Jun Shift 1)

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Question

A light whose electric field vectors are completely removed by using a good polaroid, allowed to incident on the surface of the prism at Brewster's angle. Choose the most suitable option for the phenomenon related to the prism.

JEE Main 2022 (25 Jun Shift 2)

Options

• A: Reflected and refracted rays will be perpendicular to each other.
• B: Wave will propagate along the surface of prism.
• C: No refraction, and there will be total reflection of light.
• D: No reflection. and there will be total transmission of light.

Question

‘$n$’ polarizing sheets are arranged such that each makes an angle $45°$ with the proceeding sheet. An unpolarized light of intensity $I$ is incident into this arrangement. The output intensity is found to be $\frac{I}{64}$ . The value of $n$ will be:

JEE Main 2023 (01 Feb Shift 1)

Options

• A: $3$
• B: $6$
• C: $5$
• D: $4$

Question

A beam of light consisting of two wavelengths $7000 \stackrel{\mathrm{o}}{\mathrm{A}}$ and $5500 \stackrel{\mathrm{o}}{\mathrm{A}}$ is used to obtain interference pattern in Young's double slit experiment. The distance between the slits is $2.5 \mathrm{mm}$ and the distance between the plane of slits and the screen is $150 \mathrm{cm}$. The least distance from the central fringe, where the bright fringes due to both the wavelengths coincide, is $n\times {10}^{–5} \mathrm{m}$. The value of $n$ is _____.

JEE Main 2023 (06 Apr Shift 2)

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Question

Given below are two statements :
Statement I : If the Brewster's angle for the light propagating from air to glass is ${\theta }_B$, then Brewster's angle for the light propagating from glass to air is $\frac{\pi }{2}-{\theta }_B$.

Statement II : The Brewster's angle for the light propagating from glass to air is ${\tan }^{-1}\left({\mu }_{\mathrm{g}}\right)$, where ${\mu }_{\mathrm{g}}$ is the refractive index of glass.
In the light of the above statements, choose the correct answer from the options given below :

JEE Main 2023 (24 Jan Shift 1)

Options

• A: Both Statements I and Statement II are true.
• B: Statement I is true but Statement II is false.
• C: Both Statement I and Statement II are false.
• D: Statement I is false but Statement II is true.

Question

In Young’s double slit experiment, two slits $S_1$ and $S_2$ are $d$ distance apart and the separation from slits to screen is $D$ (as shown in figure). Now if two transparent slabs of equal thickness $0.1 \mathrm{mm}$ but refractive index $1.51$ and $1.55$ are introduced in the path of beam $\left(\mathrm{\lambda }=4000 \mathrm{\AA }\right)$ from $S_1$ and $S_2$ respectively. The central bright fringe spot will shift by ________ number of fringes.

JEE Main 2023 (30 Jan Shift 1)

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Question

Monochromatic light of wavelength $500 \mathrm{~nm}$ is used in Young's double slit experiment. An interference pattern is obtained on a screen. When one of the slits is covered with a very thin glass plate (refractive index $=1.5$ ), the central maximum is shifted to a position previously occupied by the $4^{\text {th }}$ bright fringe. The thickness of the glass-plate is ______ $\mu \mathrm{m}$.

JEE Main 2024 (09 Apr Shift 2)

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Question

Two waves of intensity ratio $1 : 9$ cross each other at a point. The resultant intensities at the point, when (a) Waves are incoherent is $I_1 \left(b\right)$  Waves are coherent is $I_2$ and differ in phase by ${60}^{\mathrm{o}}$. If $\frac{I_1}{I_2}=\frac{10}{x}$, then $x=$ _________.

JEE Main 2024 (31 Jan Shift 1)

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