NEET2016PhysicsMechanical Properties of FluidsActual
Three liquids of densities, ρ 1 ,   ρ 2 and ρ 3 (with, ρ 1 > ρ 2 > ρ 3 ) , having the same value of surface tension, T , rise to the same height in three identical capillaries. The angles of contact, θ 1 ,   θ 2 and θ 3 obey
Options
- Aπ 2 > θ 1 > θ 2 > θ 3 ≥ 0
- B0 ≤ θ 1 < θ 2 < θ 3 < π 2
- Cπ 2 < θ 1 < θ 2 < θ 3 < π
- Dπ > θ 1 > θ 2 > θ 3 > π 2
Correct answer
B. 0 ≤ θ 1 < θ 2 < θ 3 < π 2
Step-by-step solution
h = 2 T cos θ r ρ g . ⇒ ρ ∝ cos θ   (as T ,   h and r are constants). Therefore, ρ ↑ ⇒ θ ↓ . θ 1 < θ 2 < θ 3 The liquid is rising, so, 0 ≤ θ 1 < θ 2 < θ 3 < π 2 .