Prism refractive index (minimum deviation) (μ = sin((A+δm)/2)/sin(A/2))

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μ = sin((A+δm)/2)/sin(A/2)

What each symbol means

SymbolWhat it stands for
AAngle of prism (apex angle) (deg or rad, consistent)
\muRefractive index of prism material (w.r.t. surrounding medium)
\delta_mAngle of minimum deviation (same angular units as A)

When to use this

Standard JEE / NCERT assumptions unless stated (paraxial, thin lens, coherent YDSE sources, etc.).