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AP EAMCET · PHYSICS · Wave Optics

In Young's double slit experiment, the two slits are illuminated by a light beam consisting of wavelengths \(4200 Å\) and \(5040 Å\). If the distance between the slits is \(2.4 \mathrm{~mm}\) and the distance between the slits and the screen is \(200 \mathrm{~cm}\), the minimum distance from the central bright fringe to the point where the bright fringes due to both the wavelengths coincide is

  1. A 0.7 mm
  2. B 1.4 mm
  3. C 2.1 mm
  4. D 2.8 mm
Verified Solution

Answer & Solution

Correct Answer

(C) 2.1 mm

Step-by-step Solution

Detailed explanation

Let \(n_1\) fringes of \(\lambda_1=4200 Å\) and \(n_2\) fringes of \(\lambda_2=5040 Å\) wavelength are formed in a fixed distance on screen. So, \(n \lambda=\) constant or \(n_1 \lambda_1=n_2 \lambda_2\) For minimum distance to be coincide,…