If capillary rise of water in 1 mm diameter tube is 3 cm, then the height of capillary rise of water in 0.2 mm diameter tube will be
- A1.5 cm
- B7.5 cm
- C15 cmCorrect
- D75 cm
Solution
Concept
Capillary rise is inversely proportional to tube diameter
Formula
h = 4σ cosθ / (ρ g d), so h ∝ 1/d
Step-by-step solution
1. h₂ / h₁ = d₁ / d₂ = 1 / 0.2 = 5. 2. h₂ = 5 × 3 cm = 15 cm.
Explanation
Capillary rise varies inversely with tube diameter. When the diameter becomes one-fifth, the rise becomes five times: 3 × 5 = 15 cm.
Shortcut
h × d = constant: 3 × 1 = h × 0.2.
Common mistake
Squaring the ratio.
Correct answer: C) 15 cm