Angle of Contact & Capillarity question from MHT CET 2026 (11 Apr, Shift 2)

Answer: (b)

1. Water rises in the annular gap; surface tension acts on both the inner wall of the tube and the wire surface.
2. Upward force (contact angle $\approx 0$): $F = T(2\pi R + 2\pi r) = 2\pi T(R + r)$.
3. Weight of column: $W = \pi(R^2 - r^2)h\rho g = \pi(R-r)(R+r)h\rho g$.
4. $F = W \Rightarrow h = \dfrac{2T}{(R-r)\rho g}$.
5. So the answer is (b) $\dfrac{2T}{(R-r)\rho g}$.