An equilateral glass prism has a minimum deviation of 30°. The refractive index of the glass is:

The critical angle for glass (n = √2) with respect to air is:

A thin prism of angle 5° and refractive index 1.5 produces a deviation of:

The dispersive power of a medium depends on:

The minimum deviation produced by a prism of angle A and refractive index n (for thin prism) is: <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 280 140" style="max-width:280px;margin:0.5em auto;display:block;"> <title>Thin prism deviating a ray by angle δ = (n−1)A</title> <rect width="280" height="140" fill="#faf9f5" rx="6"/> <defs><marker id="ah-jop01q-2" markerWidth="6" markerHeight="4" refX="6" refY="2" orient="auto"><polygon points="0,0 6,2 0,4" fill="#c6613f"/></marker></defs> <polygon points="140,20 80,110 200,110" fill="none" stroke="#14140f" stroke-width="1.8"/> <text x="140" y="15" text-anchor="middle" font-size="9" fill="#14140f">A</text> <line x1="30" y1="65" x2="110" y2="65" stroke="#c6613f" stroke-width="1.5" marker-end="url(#ah-jop01q-2)"/> <line x1="170" y1="65" x2="260" y2="80" stroke="#c6613f" stroke-width="1.5" marker-end="url(#ah-jop01q-2)"/> <line x1="170" y1="65" x2="260" y2="65" stroke="#14140f" stroke-width="0.6" stroke-dasharray="3,3"/> <path d="M230,65 A30,30 0 0,1 235,72" fill="none" stroke="#788c5d" stroke-width="0.8"/> <text x="242" y="70" font-size="8" fill="#788c5d">δ</text> <text x="140" y="132" text-anchor="middle" font-size="9" fill="#14140f">δ = (n−1)A</text> </svg>