Question

A beam of light consisting of two wavelengths 6500 A and 5200 A is used to obtain interference fringes in Young’s double slit experiment. The distance between the slits is 2 mm and the distance between the plane of the slits and the screen is 120 cm. Find the distance of the ${10}^{th}$ bright fringe from the central maximum corresponding to shorter wavelength

• A. 1.1 mm
• B. 2.6 mm
• C. 2.8 nm
• D. 3.12 mm

Answer 1

The correct option is D 3.12 mm

$d=2mm.D=120cm,\lambda =5200\dot{A}$
$y_{bright}=\frac{n\lambda D}{d}$
$y_{10}=\frac{10\times 5200\times {10}^{-10}1.2}{2\times {10}^{-3}}$
$=52\times 6\times {10}^{-5}m=3.12mm$
$y_{10}=\frac{10\lambda D}{d}$