Q: In young’s double slit experiment, how many maximum can be obtained on a screen (including the central maximum) on both sides of the central fringe if λ = 2000 A° and d = 7000 A° ?

Sol: For maximum intensity on the screen,

$\large d sin\theta = n \lambda $

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

$\large sin\theta = \frac{n \times 2000 \times 10^{-10} }{7000 \times 10^{-10} }$

$\large sin\theta = \frac{n}{3.5} $

Maximum value of sin θ = 1

∴ n = -3, -2, – 1, 0, 1, 2, 3,; ∴ 7 maximas.