Question

In a young’s double slit experiment, (slit distance d) monochromatic light of wavelength $\lambda$is used and the fringe pattern observed at a distance D from the slits. The angular position of the bright fringes are:

• A. $\sin^{- i}\left( \frac{N\lambda}{d} \right)$
• B. $\sin^{- 1}\left( \frac{(N + \frac{1}{2})\lambda}{d} \right)$
• C. $\sin^{- 1}\frac{N\lambda}{D}$
• D. $\sin^{- 1}\left( \frac{(N + \frac{1}{2})\lambda}{D} \right)$

Answer 1

Answer: (A)

$\sin^{- i}\left( \frac{N\lambda}{d} \right)$

Answer 2

The condition for bright fringes is, path difference,

$\delta = d\sin\theta_{bright} = N\lambda$

Where $N = 0, \pm 1, \pm 2$

The angular position of the bright fringes is

$\theta_{bright} = \sin^{- 1}\left( \frac{N\lambda}{d} \right)$