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PhysicsFluidSurface TensionMedium2 minPYQ_2019
PhysicsMediummultiple choice

A cylindrical capillary tube of 0.2 mm radius is made by joining two capillaries T1 and T2 of different materials having water contact angles of 0o and 60o, respectively. The capillary tube is dipped vertically in water in two different configurations, case I and II as shown in figure. Which of the following option(s) is(are) correct?
(Surface tension of water =0.075 N/m, density of water =1000 kg/m3, take g=10m/s2)

Options:(select one or more)

Answer:
A, B, C
Solution:

Heights if only single material tubes are used of sufficient length, For tableT1h1=2Tcosθprg=2×0.075×cos0Kd1000×2×10-4×10=7.5cmFor tableT2h2=2Tcosθprg=2×0.075×cos60°1000×2×10-4×10=3.75cmWeight of water in meniscus will be different in two cases because angle of contact is differentCis correct. Liquid will rise only upto height of5 cmand meniscus will adjust by changing is radius of curvature. If the liquid goes up in tube2then it will not be able to support the weight of the liquid(D)is incorrect. For option(B)Refer diagram below -AsK4maximum height upto which liquid may rise in capillary ish1=7.5cmAnd length of tube available is8 cmWater will rise upto7.5 cm(B)is correct. For option(A), Refer figure below -Here maximum height upto which water can rise in case-2,h2=3.75cm. Also the length of tube available is5 cm.Water will rise upto3.75cm(A)is correct.

Stream:JEE_ADVSubject:PhysicsTopic:FluidSubtopic:Surface Tension
2mℹ️ Source: PYQ_2019

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