Q: In young’s double slit experiment interference fringes 1° apart are produced on the screen, the slit separation is (λ = 589 nm)

Sol: The fringe width, $\large \beta = \frac{\lambda D}{d} $

The angular separation of the fringes is given by

$\large \theta = \frac{\beta}{D} = \frac{\lambda}{d} $

Given, ? = 1° = π/180 rad , λ = 589 nm

$\large d = \frac{\lambda}{\theta} $

$\large d = \frac{589 \times 10^{-9}}{\pi /180} $

= 0. 0337 mm