= Solution
A <liquid crystal> flows while retaining partial molecular order. A <nematic liquid crystal> has long-range orientational order but no crystal-like positional lattice. Its local mean axis is the <nematic director> $\mathbf n$, with $\mathbf n\equiv-\mathbf n$ for an ordinary apolar nematic. Order leads to anisotropic optical and dielectric response and an elastic cost for director distortions.
\b[Nematic order selects an axis, not a common molecular head direction or density-layer stack.] The original sketch uses short rods as a coarse-grained orientation map.
\Image[/past-exam-of-the-mphil-in-micro-and-nanotechnology-enterprise-course-of-the-university-of-cambridge/2020/paper-2-directors.png]
{title=Liquid-crystal order, defects, anchoring and cylindrical confinement}
{description=Original director sketches. Rods have no arrowheads. Sphere profiles are illustrative boundary-compatible fields, not elastic-energy minimizers. Channel panels are axial sections; the homeotropic profile escapes toward the pore axis.}
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