Capillary Action

Q.

What is capillary method?

Q. Mercury does not wet glass, wood or iron because:

1. Cohesive force is less than adhesive force.
2. Cohesive force is greater than adhesive force.
3. Angle of contact is less than ${90}^{\circ }$.
4. Cohesive force is equal to adhesive force.

Q. In outer space, if a capillary tube is dipped in water, then the water will rise to the upper end of the tube irrespective of its length.

1. False
2. True

Q. When a capillary tube is dipped in a liquid, liquid rises $0.06\text{m}$ in it. Surface tension of liquid is $0.03\text{N/m}$, density of liquid is ${10}^3{\text{kg/m}}^3$. If contact angle is ${60}^{\circ }$, then radius of capillary is (Assume $g=10{\text{m/s}}^2$)

1. $1\text{mm}$
2. $0.5\text{mm}$
3. $0.05\text{mm}$
4. $0.01\text{mm}$

Q. A liquid does not wet the surface of a solid, if the angle of contact is

1. Zero
2. Obtuse (more than ${90}^{\circ })$
3. Acute (less than ${90}^{\circ })$
4. ${90}^{\circ }\left(\text{right angle}\right)$

Q. Liquid reaches an equilibrium as shown in a capillary tube of internal radius $r=1\text{cm}$. If the surface tension of the liquid is $T=0.07\text{N/m}$. The angle of contact $\theta ={60}^{\circ }$ and density of liquid $\rho ={10}^3{\text{kg/m}}^3$, then the pressure difference between $P$ and $Q$ is


Take atmospheric pressure as ${10}^5{\text{N/m}}^2$.

1. $0.7{\text{N/m}}^2$
2. $3.5{\text{N/m}}^2$
3. $7{\text{N/m}}^2$
4. $0.2{\text{N/m}}^2$

Q. If $M$ is the mass of water that rises in a capillary tube of radius $r$, then mass of water which will rise in a capillary tube (of same material) of radius $2r$ is

1. $2M$
2. $4M$
3. $M/2$
4. $M$

Q. When a cylindrical tube is dipped vertically into a liquid, the angle of contact is ${140}^{\circ }$. When the tube is dipped with an inclination of ${40}^{\circ }$, the angle of contact is:

1. ${100}^{\circ }$
2. ${140}^{\circ }$
3. ${180}^{\circ }$
4. ${60}^{\circ }$

Q. Water rises in a capillary tube upto a height of $50\text{cm}$. The length of the water column when the capillary tube is tilted at an angle of ${45}^{\circ }$ is

1. $\frac{50}{\sqrt{2}}\text{cm}$
2. $50\sqrt{2}\text{cm}$
3. zero
4. None of these

Q. Water rises in a capillary tube to a certain height such that the upward force due to surface tension is balanced by $75\times {10}^{-4}\text{N}$ force due to the weight of the liquid. If the surface tension of water is $6\times {10}^{-2}{\text{Nm}}^{-1}$, the inner circumference of the capillary must be
(Assume angle of contact=$0$)

1. $1.25\times {10}^{-2}\text{m}$
2. $0.50\times {10}^{-2}\text{m}$
3. $6.5\times {10}^{-2}\text{m}$
4. $12.5\times {10}^{-2}\text{m}$

Q. Water rises to a height $h$ in a capillary tube of area of cross-section $a$. To what height will the water rise in a capillary tube of area of cross-section $4a$ ?

1. $\frac{h}{4}$
2. $\frac{h}{2}$
3. $2h$
4. $4h$

Q. Mercury does not wet glass, wood or iron because:

1. Cohesive force is less than adhesive force.
2. Cohesive force is greater than adhesive force.
3. Angle of contact is less than ${90}^{\circ }$.
4. Cohesive force is equal to adhesive force.

Q.

When the temperature is increased the angle of contact of a liquid

1. Increases

2. Decreases

3. Remains the same

4. First increases and then decreases

Q. A glass capillary tube is lowered vertically into liquid in a vessel.
Match the column.
$\begin{array}{cc}\text{Column 1}& \text{Column 2}\\ \text{Meniscus observed}& \text{Liquid level in capillary tube}\\ \text{A) Concave}& \text{(i) Ascends}\\ \text{B) Convex}& \text{(ii) Descends}\\ \text{C) Flat}& \text{(iii) Neither ascends nor descends}\end{array}$

1. $A\to \left(i\right);B\to \left(ii\right);C\to \left(iii\right)$
2. $A\to \left(ii\right),B\to \left(i\right);C\to \left(iii\right)$
3. $A\to \left(iii\right);B\to \left(ii\right);C\to \left(i\right)$
4. None of these.

Q. If the capillarity rise in two tubes containing same liquid and made of same material are $6.6\text{cm}$ and $2.2\text{cm}$, then the ratio of the radii of the tubes is

1. $1:3$
2. $3:1$
3. $1:2$
4. $1:6$

Q. Figure shows a capillary tube of radius $r$ dipped into water. The atmospheric pressure is $P_0$ and the capillary rise of water is $h$. $s$ is the surface tension for water-glass.


Which of the following graphs may represent the relation between the capillary rise $h$ and the radius $r$ of the capillary?

1. 
2. 
3. 
4. 

Q. The rise of the water level in a capillary tube of radius $0.07\text{cm}$ when dipped vertically in a beaker containing water (assuming it to be perfectly wetting) will be.
Given : Surface tension of water is $0.07{\text{Nm}}^{-1}$ and $g=10{\text{ms}}^{-2}$

1. $2\text{cm}$
2. $4\text{cm}$
3. $1.5\text{cm}$
4. $3\text{cm}$

Q. If the capillarity rise in two tubes containing same liquid and made of same material are $6.6\text{cm}$ and $2.2\text{cm}$, then the ratio of the radii of the tubes is

1. $1:3$
2. $3:1$
3. $1:2$
4. $1:6$

Q. The lower end of a capillary tube touches a liquid whose angle of contact is ${120}^{\circ }$, the liquid

1. rises into the tube
2. falls in the tube
3. may rise or fall inside
4. neither rises nor falls inside the tube

Q. If a capillary tube is dipped into liquid and the level of the liquid inside and outside are same, then the angle of contact is

1. $0^{\circ }$
2. ${90}^{\circ }$
3. ${45}^{\circ }$
4. ${30}^{\circ }$

Q. A glass capillary tube is lowered vertically into liquid in a vessel.
Match the column.
$\begin{array}{cc}\text{Column 1}& \text{Column 2}\\ \text{Meniscus observed}& \text{Liquid level in capillary tube}\\ \text{A) Concave}& \text{(i) Ascends}\\ \text{B) Convex}& \text{(ii) Descends}\\ \text{C) Flat}& \text{(iii) Neither ascends nor descends}\end{array}$

1. $A\to \left(i\right);B\to \left(ii\right);C\to \left(iii\right)$
2. $A\to \left(ii\right),B\to \left(i\right);C\to \left(iii\right)$
3. $A\to \left(iii\right);B\to \left(ii\right);C\to \left(i\right)$
4. None of these.

Q. Water rises in plant fibres due to

1. capillarity
2. viscosity
3. fluid pressure
4. osmosis

Q. If for a liquid in a vessel, force of cohesion is twice the force of adhesion, then identify the correct statement(s):

1. The meniscus will be convex upwards
2. The angle of contact will be obtuse
3. The liquid will descend in the capillary tube
4. The liquid will wet the surface of the vessel

Q. Water rises to a height of $10\text{cm}$ in a capillary tube and mercury falls to a depth of $\sqrt{2}\text{cm}$ in the same capillary tube. If the density of mercury is $\approx 14{\text{g/cm}}^3$ and angle of contact is ${135}^{\circ }$, the ratio of surface tension for water and mercury is (Angle of contact for water and glass is $0^{\circ }$).

1. $2:1$
2. $1:2$
3. $5:14$
4. $14:5$

Q. A capillary tube of inner diameter $r$ is lowered vertically into liquid in a vessel. The height of capillary column of liquid at a particular temperature is

1. directly proportional to the radius of the tube.
2. inversely proportional to the radius of the tube.
3. does not depend on radius of tube.
4. None of these

Q. Three liquids having densities ${\rho }_1,{\rho }_2$ and $\rho {}_3$ $({\rho }_1>{\rho }_2>{\rho }_3)$, having the same value of surface tension $T$, rise to the same height $h$ in three identical capillaries. The angle of contact ${\theta }_1,{\theta }_2$ and ${\theta }_3$ obeys

1. $\frac{\pi }{2}>{\theta }_1>{\theta }_2>{\theta }_3\ge 0$
2. $0\le {\theta }_1<{\theta }_2<{\theta }_3<\frac{\pi }{2}$
3. $\frac{\pi }{2}<{\theta }_1<{\theta }_2<{\theta }_3<\pi$
4. $\pi >{\theta }_1>{\theta }_2>{\theta }_3>\frac{\pi }{2}$

Q.

Nature of meniscus for liquid of $0^{\circ }$ angle of contact

1. Plane

2. Parabolic

3. Semi-spherical

4. Cylindrical

Q. The end of a capillary tube with radius $r$ is immersed in water. Assuming the tube to be sufficiently long, calculate the heat energy produced when the water rises in the tube.
[Assume angle of contact = $0^{\circ }$ for glass-water system, $\rho =$ density of water, $T=$ surface tension of water]

1. $\frac{2\pi T^2}{\rho g}$
2. $\frac{4\pi T^2}{\rho g}$
3. $0$
4. $\frac{\pi T^2}{\rho g}$

Q. A $20\text{cm}$ long capillary tube is dipped in water. The water rises upto $8\text{cm}$. If the entire arrangement is put in a freely falling elevator, the length of water column in the capillary tube will be

1. $8\text{cm}$
2. $10\text{cm}$
3. $4\text{cm}$
4. $20\text{cm}$

Q. A liquid of density $\rho$ and surface tension $\sigma$ rises to a height $h$ in a capillary tube of diameter $d$. The potential energy of the liquid in the capillary tube is:
[Assume liquid to be perfectly wetting in nature]

1. $h\rho g$
2. $\frac{2\pi {\sigma }^2}{\rho g}$
3. $2\pi {\sigma }^2\rho g$
4. $\frac{2\pi {\sigma }^2}{\rho gh}$