In single slit diffraction, the condition for the first minimum is:

A diffraction grating has 500 lines/mm. The maximum order visible for light of λ = 600 nm is:

The angular width of the central maximum in single slit diffraction is: <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 300 130" style="max-width:300px;margin:0.5em auto;display:block;"> <title>Single slit diffraction — central maximum angular width 2λ/a</title> <rect width="300" height="130" fill="#faf9f5" rx="6"/> <rect x="50" y="20" width="3" height="35" fill="#14140f"/> <rect x="50" y="75" width="3" height="35" fill="#14140f"/> <text x="40" y="62" text-anchor="end" font-size="8" fill="#788c5d">a</text> <line x1="53" y1="55" x2="250" y2="55" stroke="#c6613f" stroke-width="0.8" stroke-dasharray="3,3"/> <line x1="53" y1="55" x2="250" y2="30" stroke="#c6613f" stroke-width="1.2"/> <line x1="53" y1="55" x2="250" y2="80" stroke="#c6613f" stroke-width="1.2"/> <path d="M120,55 L130,47" fill="none" stroke="#788c5d" stroke-width="0.8"/> <path d="M120,55 L130,63" fill="none" stroke="#788c5d" stroke-width="0.8"/> <text x="137" y="58" font-size="8" fill="#788c5d">2λ/a</text> <rect x="250" y="20" width="3" height="90" fill="#14140f"/> <rect x="253" y="35" width="8" height="40" fill="#c6613f" opacity="0.4" rx="1"/> <text x="150" y="120" text-anchor="middle" font-size="8" fill="#14140f">Central max width = 2λD/a on screen</text> </svg>

In single slit diffraction, if the slit width is doubled, the width of the central maximum:

The resolving power of a grating with N total slits used in order n is: