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When a long glass capillary tube of radius 0.015 cm is dipped in a liquid, the liquid rises to a height of 15 cm within it. If the contact angle between the liquid and glass to close to 0°, the surface tension of the liquid, in milliNewton m–1, is [ρ(liquid) = 900 kgm–3, g = 10 ms–2] (Give answer in closest integer) _____. |
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Answer» 101 h = 2Tcos\(\theta\) / ρgr ⇒ T = (ρgr x h) / 2cos\(\theta\) = (900 x 10 x 15 x 15) / (100 x 1000 x 100 x 2) ⇒ T = 0.10125 Nm–1 ⇒ T = 101.25 \(\simeq\) 101 milliNewton m–1 |
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