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Question: Answered & Verified by Expert
The lower end of a capillary tube is dipped into water and it is observed that the water in capillary tube rises by 7.5 cm. Find the radius of the capillary tube used, if surface tension of water is 7.5×10-2 N m-1? Angle of contact between water and glass is 0° and acceleration due to gravity is 10 m s-2.
PhysicsMechanical Properties of FluidsAP EAMCETAP EAMCET 2021 (19 Aug Shift 1)
Options:
  • A 0.2cm
  • B 0.1cm
  • C 0.4mm
  • D 0.2mm
Solution:
2347 Upvotes Verified Answer
The correct answer is: 0.2mm

Height of rise of liquid due to surface tension in a capillary tube, h=2Scosθrρg

Given that, height of liquid rise h=7.5 cm, surface tension of water S=7.5×10-2 N m-1 and the angle of contact between water and glass is θ=0°

h=2Scosθrρgr=2Scosθhρg=27.5×10-2 N m-1cos0° 7.5×10-2 m1000 kg m-310 m s-2r=0.2×10-3 m or 0.2 mm

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