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JEE • PHYSICS • WAVE OPTICS

Wave optics practice · Medium

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These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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Showing 241-270 of 396 questions

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241 Medium
241 of 396
Application +4 | -1
The wavelength of the light used in Young’s double slit experiment is λ\lambda. The intensity at a point on the screen is II, where the path difference is λ6\frac{\lambda }{6}. If I0{{I_0}} denotes the maximum intensity, then the ratio of I  and  I0{I\;and\;{I_0}} is
View answer and explanation
Correct option: D
0.750.75
Option D (0.75) is correct because the ratio of intensities is calculated using the phase difference and the intensity formula in Young's double-slit experiment.
242 Medium
242 of 396
Analyzing +4 | -1
In Young’s double slit experiment the wavelength of light was changed from 7000  A  to  ∘  3500  A∘7000\;\mathop {\mathrm{A}\;to\;}\limits^ \circ \;3500\;\mathop \mathrm{A}\limits^ \circ. While doubling the separation between the slits which of the following is not true for this experiment
View answer and explanation
Correct option: D
The separation between successive dark fringes remains unchanged
Option D (The separation between successive dark fringes remains unchanged) is the correct answer because the fringe width is directly proportional to the wavelength and inversely proportional to the slit separation. Doubling the slit separation and halving the wavelength keeps the fringe width constant.
243 Medium
243 of 396
Application +4 | -1
The two coherent sources of intensity that ratio 2:82: 8 produce an interference pattern. The values of maximum and minimum intensities will be respectively. Where I1I_1 is the intensity of first source
View answer and explanation
Correct option: B
9I19 \mathrm{I}_1 and I1\mathrm{I}_1
Option B (9I19 \mathrm{I}_1 and I1\mathrm{I}_1) is correct because it correctly calculates the maximum and minimum intensities using the given intensity ratio.
244 Medium
244 of 396
Understanding +4 | -1
For Young's double slit experiment, two statements are given below:

Statement I : If screen is moved away from the plane of slits, angular separation of the fringes remains constant.

Statement II : If the monochromatic source is replaced by another monochromatic source of larger wavelength, the angular separation of fringes decreases.

In the light of the above statements, choose the correct answer from the options given below:
View answer and explanation
Correct option: A
Statement I is true but Statement II is false
Option A (Statement I is true but Statement II is false) is correct because angular separation depends on wavelength but not screen distance.
245 Medium
245 of 396
Understanding +4 | -1
In a single slit diffraction pattern with slit width aa and wavelength of light λ\lambda, find the angular position of first minima if screen distance is D(D≫a)D(D \gg a)
View answer and explanation
Correct option: A
λa\frac{\lambda}{a}
Option A (λa\frac{\lambda}{a}) is correct because the first minima in single-slit diffraction occurs at sin⁡θ=λa\sin \theta = \frac{\lambda}{a}.
246 Medium
246 of 396
Application +4 | -1
An incident plane wavefront makes angle 53∘53^{\circ} with surface of medium in air. The refracted wavefront makes angle 37∘37^{\circ} with the surface. Refractive index of medium is :-
View answer and explanation
Correct option: B
4/34 / 3
Option B (4/34 / 3) is correct because it is calculated using Snell's law, relating the angles of incidence and refraction to the refractive index.
247 Medium
247 of 396
Remembering +4 | -1
Astronomical wavelength increase due to doppler effect known as
View answer and explanation
Correct option: A
Red shift
Option A (Red shift) is correct because the Doppler effect causes an increase in wavelength (shift towards the red end of the spectrum) when an astronomical object moves away from the observer.
248 Medium
248 of 396
Understanding +4 | -1
Assertion: In interference, only redistribution of light energy occurs in the form of maximum and minimum.

Reason: Average energy in the interference pattern is smae as it would be if there were no interference.
View answer and explanation
Correct option: B
Both Assertion and Reason are true and Reason is not the correct explanation of Assertion
Option B is correct because interference involves redistribution of energy, and the average energy remains the same, but the reason doesn't directly explain the assertion.
249 Medium
249 of 396
Understanding +4 | -1
What is the path difference of destructive interference
View answer and explanation
Correct option: D
(2n+1)λ2\frac{{\left( {2n + 1} \right)\lambda }}{2}
Option D ((2n+1)λ2\frac{{\left( {2n + 1} \right)\lambda }}{2}) is correct because destructive interference occurs when the path difference is an odd multiple of half the wavelength.
250 Medium
250 of 396
Application +4 | -1
In young's experiment light of wavelength 4800 A∘4800 ~\mathop {\text{A}}\limits^ \circ is used. If one slit is covered with glass of refractive index 1.41.4 and another slit is covered with a film of same thickness having refractive index 1.7,1.7, the centre fringe shifts to the position of 5th5^{\text {th}} bright fringe then find the thickness of film.
View answer and explanation
Correct option: D
8×10−3 mm8 \times 10^{-3} \mathrm{~mm}
Option D (8×10−3 mm8 \times 10^{-3} \mathrm{~mm}) is correct because it is the thickness calculated using the formula for fringe shift due to introducing films of different refractive indices: t(μ1−μ2)=nλt(\mu_1 - \mu_2) = n\lambda.
251 Medium
251 of 396
Understanding +4 | -1
The principle of superposition is basic to the phenomenon of
View answer and explanation
Correct option: B
Interference
Option B (Interference) is correct because interference is a phenomenon that relies on the superposition principle of waves.
252 Medium
252 of 396
Understanding +4 | -1
In the phenomenon of diffraction of light, when blue light is used in the experiment instead of red light, then
View answer and explanation
Correct option: A
Fringes will become narrower
Option A (Fringes will become narrower) is correct because the fringe width in diffraction is directly proportional to the wavelength of light, and blue light has a shorter wavelength than red light.
253 Medium
253 of 396
Understanding +4 | -1
In Young’s double slit experiment, the distance between the two slits is made half, then the fringe width will become
View answer and explanation
Correct option: B
Double
Option B (Double) is correct because the fringe width is inversely proportional to the distance between the slits.
254 Medium
254 of 396
Analyzing +4 | -1
Assertion: If the phase difference between the light waves emerging from the slits of the Young's experiment is π\pi-radian, the central fringe will be dark.

Reason: Phase difference is equal to (2π/λ)(2 \pi / \lambda) times the path difference.
View answer and explanation
Correct option: B
Both Assertion and Reason are true and Reason is not the correct explanation of Assertion
Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion because the central fringe is dark due to an initial phase difference of π\pi, not directly because of the path difference formula.
255 Medium
255 of 396
Application +4 | -1
In Young’s double slit experiment we get 60 fringes in the field of view of monochromatic light of wavelength 4000  A∘{4000\;\mathop \mathrm{A}\limits^ \circ }. If we use monochromatic light of wavelength 6000  A∘{6000\;\mathop \mathrm{A}\limits^ \circ }, then the number of fringes obtained in the same field of view are
View answer and explanation
Correct option: C
40
Option C (40) is correct because the number of fringes is inversely proportional to the wavelength of light used.
256 Medium
256 of 396
Application +4 | -1
In a Young's double slit experiment the angular width of a fringe formed on a distant screen is 1∘1^{\circ}. The wavelength of the light used is 6280A∘6280\mathop {\text{A}}\limits^ \circ. What is the distance between the two coherent sources?
View answer and explanation
Correct option: A
0.036 mm
Option B (0.063 mm) is the closest to the correct answer. The angular width is related to the wavelength and slit separation by α=λd\alpha = \frac{\lambda}{d}, so d=λαd = \frac{\lambda}{\alpha}.
257 Medium
257 of 396
Understanding +4 | -1
The sky appears blue, because
View answer and explanation
Correct option: A
Blue light is scattered the most
Blue light is scattered the most, which is why the sky appears blue. This phenomenon is known as Rayleigh scattering.
258 Medium
258 of 396
Application +4 | -1
In Young's double slit experiment if the separation between coherent sources is doubled and distance of screen from slit plane is halved, then fringe width becomes
View answer and explanation
Correct option: C
One-fourth
Option C (One-fourth) is correct because the fringe width is directly proportional to the distance to the screen and inversely proportional to the separation between the slits.
259 Medium
259 of 396
Application +4 | -1
nth{n^{th}} Bright fringe if red light (λ1=7500A∘)\left( {{\lambda _1} = 7500\mathop \mathrm{A}\limits^ \circ } \right) coincides with (n+1)th{\left( {n + 1} \right)^{th}} bright fringe of green light (λ2=6000A∘)\left( {{\lambda _2} = 6000\mathop \mathrm{A}\limits^ \circ } \right). The value of n=?n = ?
View answer and explanation
Correct option: A
4
Option A (4) is correct because the condition for the coincidence of bright fringes is nλ1=(n+1)λ2n\lambda_1 = (n+1)\lambda_2, which can be solved for n.
260 Medium
260 of 396
Understanding +4 | -1
Wavefront of a wave has direction with wave motion
View answer and explanation
Correct option: B
Perpendicular
Option B (Perpendicular) is correct because the wavefront is defined as the locus of points with the same phase, and the wave motion is perpendicular to it.
261 Medium
261 of 396
Understanding +4 | -1
An optically active compound
View answer and explanation
Correct option: A
Rotates the plane polarized light
Option A (Rotates the plane polarized light) is correct because an optically active compound has the ability to rotate the plane of polarization of plane-polarized light.
262 Medium
262 of 396
Understanding +4 | -1
VO  and  VE{V_O}\;and\;{V_E} represent the velocities, μO  and  μE{\mu _O}\;and\;{\mu _E} the refractive indices of ordinary and extraordinary rays for a doubly refracting crystal. Then
View answer and explanation
Correct option: C
Vo≤VE,μo≥μE{V_o} \le {V_E},{\mu _o} \ge {\mu _E} if the crystal is calcite
Option C (Vo≤VE,μo≥μE{V_o} \le {V_E},{\mu _o} \ge {\mu _E} if the crystal is calcite) is correct because for calcite, the refractive index of the ordinary ray is greater than or equal to that of the extraordinary ray, and the velocity is inversely related.
263 Medium
263 of 396
Application +4 | -1
In Young’s double slit experiment, distance between two slits is 0.28  mm0.28\;\mathrm{mm} and distance between slits and screen is 1.4  m1.4\;\mathrm{m}. Distance between central bright fringe and third bright fringe is 0.9  cm0.9\;\mathrm{cm}, what is the wavelength of light used?
View answer and explanation
Correct option: B
6000A∘6000\mathop \mathrm{A}\limits^ \circ
Option B (6000A∘6000\mathop \mathrm{A}\limits^ \circ) is correct because the wavelength is calculated using the formula for fringe width in Young's double-slit experiment.
264 Medium
264 of 396
Understanding +4 | -1
Plane polarised light is passed through a polaroid. On viewing through the polaroid we find that when the polariod is given one complete rotation about the direction of the light, one of the following is observed
View answer and explanation
Correct option: C
There is no change in intensity
Option C (There is no change in intensity) is correct because the intensity of plane-polarized light passing through a polaroid remains constant when the polaroid is rotated about the direction of light.
265 Medium
265 of 396
Understanding +4 | -1
In single slit diffraction pattern
View answer and explanation
Correct option: D
None of the above
Option D (None of the above) is correct because in single-slit diffraction, the central fringe is the widest and brightest, and other fringes have decreasing width and intensity.
266 Medium
266 of 396
Understanding +4 | -1
Assertion : Polaroid glasses reduce glare from road or water etc.

Reason : Reflected waves are partially polarised.
View answer and explanation
Correct option: A
If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion
Option A (If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion) is correct because reflected light is partially polarized, and Polaroid glasses reduce glare by blocking this polarized light.
267 Medium
267 of 396
Application +4 | -1
A ray of light falls on a transparent glass slab with refractive index (relative to air) of 1.62\mathrm{1}\mathrm{.62}. The angle of incidence for which the reflected and refracted rays are mutually perpendicular is
View answer and explanation
Correct option: A
tan⁡−1  (1.62){\tan ^{ - 1}}\,\,\left( {1.62} \right)
Option A (tan⁡−1  (1.62){\tan ^{ - 1}}\,\,\left( {1.62} \right)) is correct because it is derived from the relationship between refractive index and the angle of incidence when reflected and refracted rays are perpendicular.
268 Medium
268 of 396
Understanding +4 | -1
When both the components of electric field of light waves are present such that one is stronger than the other and such light is viewed through a rotating analyser, one sees a maximum and a minimum of intensity but not complete darkness. This kind of light is called
View answer and explanation
Correct option: C
Partially polarised
Option C (Partially polarised) is correct because the light exhibits a maximum and minimum intensity, but not complete darkness, indicating a partially polarized state.
269 Medium
269 of 396
Remembering +4 | -1
Wavefront means
View answer and explanation
Correct option: A
All particles in it have same phase
Option A (All particles in it have same phase) is correct because a wavefront is defined as a surface containing points affected by a wave that are all in the same phase.
270 Medium
270 of 396
Application +4 | -1
In Young’s double slit experiment, when violet light of wavelength 4358A∘4358\mathop \mathrm{A}\limits^ \circ is used, the 84 fringe are seen in the field of view, but when sodium light of certain wavelength is used, then 62 fringes are seen in the field of view, the wavelength of sodium light is
View answer and explanation
Correct option: B
5904A∘5904\mathop \mathrm{A}\limits^ \circ
Option B (5904A∘5904\mathop \mathrm{A}\limits^ \circ) is correct because the fringe width is inversely proportional to the wavelength, and the field of view remains the same.
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