Exams › JEE Advanced › Physics

In a Young's double slit experiment (YDSE) performed in a medium of refractive index 4/3, light of wavelength 600 nm in vacuum falls on slits separated by 0.45 mm. The lower slit S2 is covered by a thin glass sheet of thickness 10.4 micrometers and refractive index 1.5. The screen is placed 1.5 m from the slits. Find the location of the central maximum (in mm) on the y-axis from the central point O.

1. 1
2. 2
3. 3
4. 4

Correct answer: 4

Solution

Extra optical path (in medium) due to sheet = t*(mu_glass - mu_medium) = 10.4e-6*(1.5 - 4/3) = 10.4e-6*(1/6) m. Wait: extra path in vacuum equivalent = t*(mu_glass/mu_medium - 1)... shift y = D*t*(mu_glass - mu_medium)/(d * lambda_medium)... Let me use: extra number of wavelengths = t*(mu_glass - mu_medium)/lambda_vacuum = 10.4e-6*(1.5-4/3)/600e-9 = 10.4e-6*(1/6)/600e-9 = (10.4/6)/0.6 = 1.733/0.6 approx 2.89 fringes. Fringe width in medium = lambda_vacuum*D/(n_medium*d) = 600e-9*1.5/(4/3 * 0.45e-3) = 900e-9/(0.6e-3) = 1.5e-3 m = 1.5 mm. Shift = 2.89 * 1.5 mm = 4.33 mm ≈ 4 mm.

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 →