Question

In a Young’s double slit experiment, the slits are separated by 0.30 mm and the screen is kept 1.5 m away. The wavelength of light used is 600 nm. Calculate the distance between the central bright fringe and the 4^th dark fringe.

Answer 1

Position of dark fringe \(X_D = \frac{(2n-1)\lambda D}{2d}\)

For fourth dark n = 4

\(X_D = \frac{(2\times4-1)\lambda D}{2d}\)

\(\left(\frac{7\lambda D}{2d}\right)\)

D = 1.5 m, d = 0.30 mm, \(\lambda = 600\ nm\)

On putting these value in above equation

= 10.5 × 10^–3 m

= 10.5 mm