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2026 18 questions

Q362026 · 6 Apr 2026 · Shift 1
In interference experiment the path difference between two interfering waves at a point $A$ on the screen is $λ /3$ , where $λ$ is the wavelength of these waves, and at another point $B$ the path difference is $λ /6$ . The ratio of intensities at points $A$ and $B$ is ____.
1. A.3
2. B.4
3. C.1/3
4. D.1/4
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Answer: C
Q472026 · 6 Apr 2026 · Shift 1· Numerical answer
An unpolarized light of intensity $I_{o}$ 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 $\frac{3}{8} I_{o}$ , the angle of rotation of the light by the solution with respect to analyser is ____ degrees.
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Answer: 30
Q452026 · 6 Apr 2026 · Shift 2
1. A. $4000$
2. B. $3000$
3. C. $2000$
4. D. $1000$
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Answer: A, C
Q392026 · 5 Apr 2026 · Shift 1
In Young's double slit experiment, the fringe width of the interference pattern produced on the screen is $2.4 μ m$ . If the experiment is carried out in another medium having refractive index $1.2$ , the fringe width will be ____ $μ m$ .
1. A.1.2
2. B.2
3. C.2.4
4. D.2.88
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Answer: B
Q422026 · 5 Apr 2026 · Shift 2
The maximum intensity in a Young's double slit experiment is $I_{\circ}$ . Distance between the slits ( $d$ ) is $5 λ$ , where $λ$ is the wavelength of light used. The intensity of the fringe, exactly opposite to one of the slits on the screen, placed at $D = 10 d$ is ____.
1. A. $\frac{I _{\circ}}{4}$
2. B. $\frac{I _{\circ}}{2}$
3. C. $I_{\circ}$
4. D. $\frac{3 I _{\circ}}{4}$
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Answer: B
Q332026 · 4 Apr 2026 · Shift 1
1. A. $\frac{D λ}{a}$
2. B. $1.5 \frac{D λ}{a}$
3. C. $2 \frac{D λ}{a}$
4. D. $3 \frac{D λ}{a}$
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Answer: C
Q452026 · 4 Apr 2026 · Shift 1
1. A. $(E_{x} \hat{i} + E_{y} \hat{j}) sin (k x - k z - ω t)$
2. B. $(E_{x} \hat{i} + E_{z} \hat{k}) sin (k x + k y - ω t)$
3. C. $(E_{x} \hat{j} + E_{y} \hat{k}) sin (k y + k z - ω t)$
4. D. $(E_{x} \hat{i} + E_{y} \hat{j} + E_{z} \hat{k}) sin (k x + k y - k z - ω t)$
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Answer: A
Q422026 · 4 Apr 2026 · Shift 2
An unpolarized light of certain intensity passes through a combination of two polarizers whose transmission axes are at $3 0^{\circ}$ and $9 0^{\circ}$ , respectively, with respect to the horizontal axis. A third polarizer with its transmission axis at $6 0^{\circ}$ with the horizontal axis is placed between the two existing polarizers. The ratio of the output intensities with and without the third polarizer is ____.
1. A.3/4
2. B.4/3
3. C.9/4
4. D.4/9
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Answer: C
Q502026 · 4 Apr 2026 · Shift 2· Numerical answer
In a double slit experiment, when one of the slits is covered by a transparent mica sheet of refractive index $1.56$ , the central fringe shifts to the position of $7^{th}$ bright fringe, obtained with both slits uncovered. If the light source wavelength is $450 nm$ , the thickness of mica sheet is $α \times 1 0^{- 9} m$ . The value of $α$ is ____.
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Answer: 5625
Q462026 · 2 Apr 2026 · Shift 1· Numerical answer
In single slit diffraction pattern, the wavelength of light used is $628 nm$ and slit width is $0.2 mm$ , the angular width of central maximum is $α \times 1 0^{- 2} degrees$ . The value of $α$ is ____.
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Answer: 36
Q462026 · 2 Apr 2026 · Shift 2· Numerical answer
In a Young's double slit experiment, the intensity at some point on the screen is found to be $\frac{3}{4}$ times of the maximum of the interference pattern. The path difference between the interfering waves at this point is $\frac{λ}{x}$ where $λ$ is wavelength of the incident light. The value of $x$ is ____.
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Answer: 6
Q482026 · 28 Jan 2026 · Shift 2· Numerical answer
A beam of light consisting of wavelengths 650 nm and 550 nm illuminates the Young's double slits with separation of 2 mm such that the interference fringes are formed on a screen, placed at a distance of 1.2 m from the slits. The least distance of a point from the central maximum, where the bright fringes due to both the wavelengths coincide, is ________ $\times 1 0^{- 5} m$ .
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Answer: 429
Q332026 · 24 Jan 2026 · Shift 1
An unpolarised light is incident at an interface of two dielectric media having refractive indices of 2 (incident medium) and $23$ (medium) respectively. To satisfy the condition that reflected and refracted rays are perpendicular to each other, the angle of incidence is ____
1. A. $4 5^{\circ}$
2. B. $6 0^{\circ}$
3. C. $1 0^{\circ}$
4. D. $3 0^{\circ}$
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Answer: B
Q492026 · 23 Jan 2026 · Shift 1· Numerical answer
In two separate Young's double-slit experimental set-ups and two monochromatic light sources of different wavelengths are used to get fringes of equal width. The ratios of the slits separations and that of the wavelengths of light used are $2 : 1$ and $1 : 2$ respectively. The corresponding ratio of the distances between the slits and the respective screens $(D_{1} / D_{2})$ is ____ .
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Answer: 4
Q452026 · 23 Jan 2026 · Shift 2
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 and glass are 1.00 and 1.52, respectively.)
1. A. $36. 3^{\circ}$
2. B. $39. 6^{\circ}$
3. C. $42. 6^{\circ}$
4. D. $32. 3^{\circ}$
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Answer: D
Q432026 · 21 Jan 2026 · Shift 1
In a double slit experiment the distance between the slits is 0.1 cm and the screen is placed at 50 cm from the slits plane. When one slit is covered with a transparent sheet having thickness $t$ and refractive index $n (= 1.5)$ , the central fringe shifts by 0.2 cm . The value of $t$ is ____ cm.
1. A. $6.0 \times 1 0^{- 3}$
2. B. $8 \times 1 0^{- 4}$
3. C. $5.0 \times 1 0^{- 3}$
4. D. $5.6 \times 1 0^{- 4}$
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Answer: B
Q332026 · 21 Jan 2026 · Shift 2
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 increase when monochromatic source is replaced by another monochromatic source of higher wavelength In the light of the above statements, choose the correct answer from the options given below :
1. A.Both Statement I and Statement II are true
2. B.Statement I is true but Statement II is false
3. C.Statement I is false but Statement II is true
4. D.Both Statement I and Statement II are false
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Answer: C
Q502026 · 21 Jan 2026 · Shift 2· Numerical answer
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 center bright fringe shifts by 20 mm on the screen. The refractive index of transparent sheet is given by $\frac{α}{10}$ , where $α$ is ____.
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Answer: 14