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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 391-396 of 396 questions

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391 Medium

391 of 396

Understanding +4 | -1

In a Young’s double slit experiment, the source illuminating the slits is changed from blue to violet. The width of the fringes

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Correct option: B

Decreases

Option B (Decreases) is correct because the fringe width is directly proportional to the wavelength, and violet light has a shorter wavelength than blue light.

392 Medium

392 of 396

Remembering +4 | -1

Fraunhoffer spectrum is

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Correct option: A

Line absorption spectrum

Option A (Line absorption spectrum) is correct because Fraunhofer lines are dark lines in the solar spectrum caused by absorption of specific wavelengths by elements in the Sun's atmosphere.

393 Medium

393 of 396

Understanding +4 | -1

Light of wavelength

2000 \mathrm{~A}^{\circ}

falls on a plane reflecting surface. The wavelength of the reflected light will be

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Correct option: D

2 \times 10^{-7} \mathrm{~m}

Option D is correct because the wavelength of light does not change upon reflection from a plane reflecting surface.

394 Medium

394 of 396

Application +4 | -1

Two sources of light of wavelengths

2500 \mathop {\text{A}}\limits^{\text{o}}

and

3500 \mathop {\text{A}}\limits^{\text{o}}

are used in Young's double slit expt. simultaneously. Which orders of fringes of two wavelength patterns coincide?

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Correct option: B

7 th order of

1 \mathrm{st}

and 5 th order of 2nd

Option B (7 th order of

1 \mathrm{st}

and 5 th order of 2nd) is correct because the 7th fringe of the first wavelength coincides with the 5th fringe of the second wavelength.

395 Medium

395 of 396

Understanding +4 | -1

In Fraunhofer diffraction experiment,

L

is the distance between screen and the obstacle,

b

is the size of obstacle and

\lambda

is wavelength of incident light. The general condition for the applicability of Fraunhofer diffraction is

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Correct option: C

\frac{{{b^2}}}{{L\lambda }} < < 1

Option C is correct because the Fraunhofer diffraction condition requires the Fresnel number to be much less than 1, which is equivalent to the given inequality.

396 Medium

396 of 396

Understanding +4 | -1

In a YDSE, if the slits are of unequal widths,

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Correct option: B

the positions of minimum intensity will not be completely dark

Option B is correct. Due to unequal widths, the interfering waves have different amplitudes, leading to incomplete destructive interference and non-zero minimum intensity.

Revision notes and key takeaways

Review WAVE OPTICS in your textbook or class notes, then use this set to check your understanding.

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Wave optics practice · Medium

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