Answer to Question #90080 in Optics for Shivam Nishad

Question

The diffraction bands are of variable thickness,
whereas interference bands are equidistant'.
Discuss the validity of this statement with
reference to the diffraction pattern of a straight
edge.

Answer 1

The intensity profile can be calculated using the Fraunhofer diffraction equation as

$$I(θ)=I_0\sin {c^2 \frac { d\pi}{\lambda}\sin θ}$$

where I(θ) is the intensity at a given angle,

I₀ is the original intensity

The distance between fringes is given by

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

where x is the distance to the screen,

d is the is the distance between the slits

In this way, the diffraction bands are of variable thickness because  all diffraction bands are of different intensities.