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.