Question

A double-slit diffraction pattern is formed on a distant screen. If the separation between the slits decreases, then

Answer 1

Answer:

• this shows that on decreasing the distance between the slits:

• the distance from the central fringe will increase.

• order of fringes will decrease.

Explanation:

We have the mathematical expression for the Young's double slit experiment as:

$\lambda=\frac{x.d}{n.l}$ .....................(1)

where:

$\lambda$ = wavelength of the monochromatic light used.

x = distance from the central fringe

n = order of fringes

d = distance between the slits.

l = distance between the slit and the screen.

Equation (1) can be re-written as:

$d=\frac{\lambda.n.l}{x}$

• this shows that on decreasing the distance between the slits:

• the distance from the central fringe will increase.

• order of fringes will decrease.

While the frequency of light will be constant & distance between the slit and the screen is also kept constant.

Answer 2

Answer:

$y = \frac{ \lambda D}{d}$

From the expression given above we can notice that if separation between the given slits decreased then distance between fringes increase. since the distance between any two fringes is inversely proportional to separation between any given plates. Therefore, distance between the fringes increased

Explanation:

The distance between interference fringe for small angle is

$y = \frac{ \lambda D}{d}$

here,

\lambda denote wavelength of light

D is the distance between slits and the screen

d is separation of silts

From the expression given above we can notice that if separation between the given slits decreased then distance between fringes increase. since the distance between any two fringes is inversely proportional to separation between any given plates. Therefore, distance between the fringes increased