JEE Advanced2019PhysicsMechanical Properties of FluidsActual
A cylindrical capillary tube of 0.2 m m radius is made by joining two capillaries T 1 and T 2 of different materials having water contact angles of 0 o and 60 o , 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 k g / m 3 ,
Options
- AFor case II, if the capillary joint is 5 c m above the water surface, the height of water column raised in the
- BFor case I, if the joint is kept at 8 c m above the water surface, the height of water column in the tube will
- CThe correction in the height of water column raised in the tube, due to weight of water contained in the menis
- DFor case I, if the capillary joint is 5 c m above the water surface, the height of water column raised in the
Correct answer
A. For case II, if the capillary joint is 5 c m above the water surface, the height of water column raised in the
Step-by-step solution
Heights if only single material tubes are used of sufficient length, For table T 1 ⇒ h 1 = 2 T c o s θ p r g = 2 × 0.075 × c o s 0 K d 1000 × 2 × 10 - 4 × 10 = 7.5 c m For table T 2 ⇒ h 2 = 2 T c o s θ ′ p r g = 2 × 0.075 × c o s 60 ° 1000 × 2 × 10 - 4 × 10 = 3.75 c m Weight of water in meniscus will be different in two cases because angle of contact is different ⇒ C is correct. Liquid will rise only upto height of 5 c m and meniscus will adjust by changing is radius of curvature. If the liquid goes up in tube 2 th