In a double slit experiment, the distance between the slits is d. The screen is at a distance D from the slits. If a bright fringe is formed opposite to one of the slits, its order is

Question

In a double slit experiment, the distance between the slits is d. The screen is at a distance D from the slits. If a bright fringe is formed opposite to one of the slits, its order is (A) (d/λ) (B) (λ2/dD) (C) (D2/2λ d) (D) (d2/2Dλ)

Tardigrade Admin · Accepted Answer

When a bright fringe is formed opposite to one of the slits,

x = \frac{d}{2}

Path difference

= \frac{x d}{D}

= \frac{d}{2} \times \frac{d}{D} = \frac{d ^{2}}{2 D}

If it is

n^{t h}

order bright fringe,
Path differnce,

nλ = \frac{d ^{2}}{2 D}

or

n = \frac{d ^{2}}{2 D λ}

Q. In a double slit experiment, the distance between the slits is $d$ . The screen is at a distance $D$ from the slits. If a bright fringe is formed opposite to one of the slits, its order is

$\frac{d}{λ}$

$\frac{λ ^{2}}{d D}$

$\frac{D ^{2}}{2 λ d}$

$\frac{d ^{2}}{2 D λ}$

When a bright fringe is formed opposite to one of the slits, $x = \frac{d}{2}$
Path difference $= \frac{x d}{D}$
$= \frac{d}{2} \times \frac{d}{D} = \frac{d ^{2}}{2 D}$
If it is $n^{t h}$ order bright fringe,
Path differnce, $nλ = \frac{d ^{2}}{2 D}$ or $n = \frac{d ^{2}}{2 D λ}$

Q. In a double slit experiment, the distance between the slits is d. The screen is at a distance D from the slits. If a bright fringe is formed opposite to one of the slits, its order is

λd​

dDλ2​

2λdD2​

2Dλd2​