EASY

Earn 100

A narrow tube of radius $1 m m$ made out of soda lime glass is dipped in a tank containing mercury. The angle of contact of mercury with the surface of the glass is $140^{0}$ and surface tension of mercury at the temperature of the experiment is $0.465 N m^{- 1}$ . Mercury dips down in the tube through a depth of : (Density of mercury $= 13.6 \times 10^{3} k g m^{- 3}$ , $\cos 40 ° = 0.766$ )

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Important Questions on Viscosity and Surface Tension

EASY

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

Water rises to a height 'h' in capillary tube. If the length of capillary tube above the surface of water is made less than 'h', then:

EASY

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

Water rises upto a height

h

in a capillary tube on the surface of the earth. The value of

h

increases, if the capillary tube apparatus is kept

EASY

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

In a capillary tube experiment, a vertical,

30 cm

long capillary tube is dipped in water. The water rises upto a height of

10 cm

due to capillary action. If this experiment is conducted in a freely falling elevator, the length of the water column becomes

HARD

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

A uniform capillary tube of inner radius

r

is dipped vertically into a beaker filled with water. The water rises to a height

h

in the capillary tube above the water surface in the beaker. The surface tension of water is

σ

. The angle of contact between water and the wall of the capillary tube is

θ

. Ignore the mass of water in the meniscus. Which of the following statements is (are) true?

EASY

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

' 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 radius

' 2 r'

is:

MEDIUM

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

Two capillary tubes

P

and

Q

are dipped vertically in water. The height of water level in capillary tube

P

{(\frac{2}{3})}^{r d}

of the height in capillary tube

Q .

The ratio of their diameter is

EASY

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

Water rises to a height of

15 mm

in a capillary tube having cross-sectional area

A

. If cross-sectional area of the tube is made

\frac{A}{3}

then the water will rise to a height of

HARD

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

Obtain an expression for the rise of a liquid in a capillary tube.

EASY

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

Two light balls are suspended as shown in figure. When a stream of air passes through the space between them, the distance between the balls will

Question Image

MEDIUM

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

A capillary tube made of glass of radius

0.15 mm

is dipped vertically in a beaker filled with methylene iodide (surface tension

= 0.05 N m^{- 1}

, density

= 667 kg m^{- 3}

) which rises to height

h

in the tube. It is observed that the two tangents drawn from liquid-glass interfaces (from opp. sides of the capillary) make an angle of

60 º

with one another. Then

h

is close to (

g = 10 m s^{- 2}

)

MEDIUM

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

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 \times 10^{- 2} N m^{- 1}

? Angle of contact between water and glass is

0 °

and acceleration due to gravity is

10 m s^{- 2}

MEDIUM

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

A capillary tube is immersed vertically in water and the height of the water column is

x

. When this arrangement is taken into a mine of depth d, the height of the water column is

y

. If R is the radius of earth, the ratio

\frac{x}{y}

is :

MEDIUM

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

Liquid

A

rises to a height of

10 cm

in a capillary tube and liquid

B

falls to a depth of

2 cm

in the same tube. The density of

A

and

B

are

1 g / {cm}^{3}

and

10 g / {cm}^{3}

respectively. The contact angle of

A

and

B

with the tube is

0 °

and

135 °

respectively. If the surface tension of

A

and

B

are

S_{A}

and

S_{B}

then the ratio

\frac{S_{B}}{S_{A}}

EASY

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

The rise of liquid in capillary is more than that of water in the same capillary. Which one of the following is the CORRECT reason?

MEDIUM

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

Water rises up in a glass capillary upto a height of

9 cm

, while mercury falls down by

3.4 cm

in the same capillary. Assume the angles of contact for water-glass and mercury-glass are

0 °

and

135 °

, respectively. The ratio of surface tensions of mercury and water is (Take,

\cos 135 ° = - 0.71

)

EASY

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

When two capillary tubes of different diameters are dipped in liquid vertically, the rise of the liquid in the capillary tube is

MEDIUM

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

What is capillarity? Give any two applications of capillarity.Calculate the work done in blowing a soap bubble of radius

0.1 m

(Surface tension of soap solution

0.1 dyne cm

)

MEDIUM

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

A capillary tube of radius

r

is immersed in water and water rises in it to a height

h

. The mass of the water in the capillary is

5 g

. Another capillary tube of radius

2 r

is immersed in water. The mass of water that will rise in this tube is:

MEDIUM

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

The ratio of surface tensions of mercury and water is given to be

7.5

, while the ratio of their densities is

13.6

. Their contact angles, with glass, are close to

135 °

and

0 °

, respectively. If it is observed that mercury gets depressed by an amount

h

in a capillary tube of radius

r_{1}

, while water rises by the same amount

h

in a capillary tube of radius

r_{2}

, then the ratio

\frac{r_{1}}{r_{2}}

is close to

EASY

Physics>Mechanics>Viscosity and Surface Tension>Capillarity and Capillary Action

Three liquids of densities,

ρ_{1}, ρ_{2}

and

ρ_{3}

(with,

ρ_{1} > ρ_{2} > ρ_{3})

, having the same value of surface tension,

T

, rise to the same height in three identical capillaries. The angles of contact,

θ_{1}, θ_{2}

and

θ_{3}

obey

Important Questions on Viscosity and Surface Tension

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