In a Young's double slit experiment, the slits are separated by 0 ....

The distance between ${n}^{th}$ bright fringe on both side of central maxima is $2 . 4cm .$ The $f = ?$

$\Deltay = \dfrac{D\lambda}{d} \times 8$
$\lambda = \dfrac{d\Deltay}{8D} = \dfrac{0 . 3 \times {10}^{- 3} \times 2 . 4 \times {10}^{- 2}}{8 \times 1 . 5} = \dfrac{0 . 12 \times {10}^{- 5}}{2} = 0 . 06 \times {10}^{- 5}$
$\lambda = 6 \times {10}^{- 7}m$
$f = \dfrac{C}{6 \times {10}^{- 7}} = 0 . 5 \times {10}^{+ 15}$
$f = 5 \times {10}^{14}Hz$
So, $x = 5$