Comparison Note — Liquid Drop vs Soap Bubble vs Capillary Rise — Notes

Property	Liquid Drop	Soap Bubble	Capillary Rise
Free surfaces	1 (outer only)	2 (inner + outer)	1 (liquid-air meniscus)
Excess pressure formula	$\Delta P$ = 2S/R	$\Delta P$ = 4S/R	— (not excess pressure)
Height / Rise formula	—	—	h = 2S cosθ / (ρgr)
Contact angle relevance	No	No	Yes (θ < 90° → rise; θ > 90° → depression)
Energy relation	E = S × $\Delta A$	E = S × 2 $\Delta A$ (two surfaces)	E = mgh = work against gravity
Common NEET trap	Confusing with bubble	Confusing with drop	Forgetting cosθ factor
Example material	Water drop	Soap solution	Water-glass (rise), mercury-glass (depression)