Hey, physics enthusiasts! 🚀🌌 Let's dive into the fascinating world of single-slit diffraction, an exciting phenomenon of wave optics! 🌈🔍

Introduction: When plane waves hit a single slit of width b, they are divided into many individual wavelets, which then expand as circular waves. This phenomenon is called diffraction.

• Diffraction Minima: The positions of the diffraction minima (dark fringes) can be modeled using destructive interference and superposition.
• Huygens' Principle: Every point on a wavefront acts as a source of secondary wavelets.

• Point Sources: The first diffraction minimum is modeled by considering a point source A at the edge of the slit and another point source halfway down the slit at B.
• Destructive Interference: Every point source in the top half of the slit has a counterpart in the bottom half. They interfere destructively, canceling out to give zero intensity at the first diffraction minimum.
• Phase Difference: Each pair of wavelets arrives exactly π out of phase. For this, the light from the bottom source must travel half a wavelength (𝜆/2) more than the light from the upper source. This is the path difference between the two waves.
• Geometry of Diffraction: The extra distance traveled by the bottom source is equal to b/2 sin θ1. By equating this with 𝜆/2, we get sin θ1 = 𝜆/b and for small angles, θ1 ≈ 𝜆/b. This is the angular position of the first diffraction minimum.