A capillary tube is dipped into water. Find the height of capillary rise for T = 0.072 N/m, radius r = 5 mm and g = 10 m/s². Assume ρwater = 1000 kg/m³ and zero contact angle.
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Question

A capillary tube is dipped into water. Find the height of capillary rise for T = 0.072 N/m, radius r = 5 mm and g = 10 m/s². Assume ρwater = 1000 kg/m³ and zero contact angle.

G1 Physics · Accepted Answer

Step 1: Capillary rise is h = 2T cosθ/(ρgr). Step 2: For water wetting a clean glass tube, take θ ≈ 0 and cosθ ≈ 1. Step 3: Convert radius r = 5 mm = 5 × 10⁻³ m. Step 4: h = 2 × 0.072/(1000 × 10 × 5 × 10⁻³) = 0.144/50 = 0.00288 m. Step 5: Convert to millimetres: h = 2.88 mm. Final answer: 2.9 mm approximately (Option B).