Question

How does the spacing of bright fringes in the two slit arrangement change when we increase the spacing between the slits?

Answer 1

Explanation:

The spacing between two bright fringes in the interference pattern produced by the two-slit is given by the following formula:

$∆x=\frac{\lambda D}{d}$

In the above formula,

D is the distance to the screen

d is the separation of the two slits

is the wavelength of light

$\lambda$ is the fringe spacing

From the above formula, we notice that increasing the spacing between the slits will decrease the spacing of bright fringes.

The central maxima are widest, the secondary maxima are narrower and narrower outwards, and the minima are wider and wider outwards. The fringes are not evenly spaced or of the same width.

Therefore, as the distance between the slits increases, the width of the fringes decreases, resulting in thinner fringes.