Exams › JEE Advanced › Physics

Regarding Young's double-slit experiment and the dependence on the wavelength of light used, which of the following statements is correct? (A) A larger wavelength gives a larger fringe width. (B) The position of the central maximum depends on the wavelength. (C) With white light, violet forms its first maximum closest to the central maximum. (D) The central maxima of all wavelengths coincide.

1. A larger wavelength gives a larger fringe width.
2. The position of the central maximum depends on the wavelength of light used.
3. With white light, violet forms its first maximum closest to the central maximum.
4. Only statements (A), (C) and (D) are correct; statement (B) is wrong.

Correct answer: Only statements (A), (C) and (D) are correct; statement (B) is wrong.

Solution

Fringe width beta = lambda*D/d increases with wavelength, so (A) is correct. The central maximum is at zero path difference, independent of wavelength, so its position does NOT depend on wavelength: (B) is false, and consequently the central maxima of all wavelengths coincide, making (D) correct. The first-order maximum is at x1 = lambda*D/d, so the shortest visible wavelength (violet) has its first maximum nearest the center, making (C) correct. Therefore A, C and D are correct while B is incorrect.

Related JEE Advanced Physics questions

• What factor influences the visibility of fringes in an interference pattern?
• When the screen is moved further along the x-axis away from the source, which of the following statements is false?
• In the Young's double slit experiment using a monochromatic light of wavelength λ, the path difference (in terms of an integer n) corresponding to any point having half the peak intensity is
• Using the expression 2d sin θ = λ, one calculates the values of d by measuring the corresponding angles θ in the range 0 to 90°. The wavelength λ is exactly known and the error in θ is constant for all values of θ. As θ increases from 0°:
• Two coherent point sources separated by a distance d = 5 micrometers emit light of wavelength lambda = 2 micrometers in phase. A circular wire of radius R = 20 micrometers is placed symmetrically around the two sources (sources lie along a diameter). Points A and B are at the ends of the diameter along the line joining the sources; points C and D are at the ends of the diameter perpendicular to the line joining the sources. Which of the following is correct?
• Young's double slit experiment is performed in a medium of refractive index mu1 = 4/3. A thin transparent slab of refractive index mu2 = 3/2 and thickness t = 8 micrometers is placed in front of slit S2. The magnitude of the optical path difference (with respect to the liquid medium) at the central point O is:

⚔️ Practice JEE Advanced Physics free + battle 1v1 →