 Solution

ID: past-exam-of-the-quantum-condensed-matter-course-of-the-university-of-cambridge/2008/section-a/a4/d/ii/solution

Codex  0 Created 2026-10-18 Updated 2026-10-20

For the planar good-solvent coil,

R \sim ℓ N^{3/4}

ϕ^{*} \sim \frac{N ℓ ^{2}}{ℓ ^{2} N ^{3/2}} = N^{- 1/2}, ϕ^{*} \sim 1 0^{- 2} = 1%.

This is a scaling estimate; the monomer geometry and choice of coil radius set order-one numerical factors.

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