Waves & Optics · Physics

Diffraction is the wave spreading you cannot ignore.

Learn why apertures produce patterns, how gratings separate wavelengths, and how diffraction sets a fundamental resolution limit.

This topic

Diffraction

Treat diffraction as a consequence of finite apertures. Patterns encode wavelength and geometry.

Pattern

Single-slit diffraction

A single narrow slit produces a wide central maximum with weaker side maxima. The key idea is interference between contributions across the slit width.

Central maximum and minima positions (conceptual)
Why narrower slits spread more
Geometry: angle vs screen position (intro)
Common misconceptions about “shadow”

Device

Diffraction gratings

A grating has many equally spaced slits, producing sharp principal maxima. Gratings are powerful for separating wavelengths and measuring spectra.

Many-slit interference intuition
Order number and principal maxima
Why maxima become sharp
Wavelength measurement idea

Limit

Resolution limits

Diffraction sets a fundamental limit on how closely two objects can be distinguished. Larger apertures improve resolution by reducing diffraction spreading.

What “resolution” means physically
Aperture size and resolving power
Qualitative Rayleigh criterion idea
Examples: telescopes and microscopes

Practice

Practice & Exercises

Practice predicting diffraction spread, interpreting grating behavior, and reasoning about resolution improvements.

Single-slit conceptual and numeric drills
Grating order and wavelength questions
“Which setup resolves better?” comparisons
Short explanations of aperture effects
Exam-style diffraction sets