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A liquid will not wet the surface of a solid, if the angle of contact is

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Important Questions on Viscosity and Surface Tension

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

Which one of the following statement is correct?

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

A glass capillary tube is of the shape of a truncated cone with an apex angle

α

so that its two ends have cross-sections of different radii. When dipped in water vertically, the water rises in it to a height

h

, where the radius of its cross-section is

b

. If the surface tension of water is

S

, its density is

ρ

, and its contact angle with glass is

θ

, then the value of

h

will be (

g

is the acceleration due to gravity)

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

' 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:

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

Two separate soap bubbles of radii

3 \times 10^{- 3} m

and

2 \times 10^{- 3} m

respectively, formed of same liquid (surface tension

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

) come together to form a double bubble. The radius of interface of double bubble is

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

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:

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

Pressure inside two soap bubbles are

1.01

and

1.02

atmosphere, respectively. The ratio of their volumes is :

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

A soap bubble having radius of

1 m m

is blown from a detergent solution having a surface tension of

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

The pressure inside the bubble equals at a point

Z_{0}

below the free surface of water in a container. Taking

g = 10 m s^{- 2},

density of water

= 10^{3} k g m^{- 3},

the value of

Z_{0}

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

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

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

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

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

A rectangular film of liquid is extended from

(4 cm \times 2 cm)

(5 cm \times 4 cm)

. If the work done is

3 \times 10^{- 4} J

, the value of the surface tension of the liquid is

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

The surface tension of the soap water solution is

\frac{1}{10 π} N m^{- 1}

. The free energy of the surface layer of a soap bubble of diameter

5 mm

will be

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): Clothes containing oil or grease stains cannot be cleaned by water wash.

Reason (R): Because the angle of contact between the oil/grease and water is obtuse. In light of the above statements, choose the correct answer from the option given below.

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

A wire of length

10 cm

is gently placed horizontally on the surface of water having a surface tension of

75 \times 10^{- 3} N m^{- 1}

. What force is required to just pull up the wire from the water surface?

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

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

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

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

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

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?

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

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

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

When one end of the capillary is dipped in water, the height of the water column is

h

. The upward force of

105 dyne

due to surface tension is balanced by the force due to the weight of the water column. The inner circumference of the capillary is
(Surface tension of water

= 7 \times 10^{- 2} N m^{- 1})

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

The radius

R

of the soap bubble is doubled under isothermal condition. If

T

be the surface tension of the soap bubble, the work done in doing so is given by

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Physics>Mechanics>Viscosity and Surface Tension>Angle of Contact

Identify the incorrect statement about 'angle of contact':
(a) Angle of contact depends upon the inclination of the solid surface to the liquid surface.
(b) If the angle of contact of a liquid and a solid surface is less than

90 °,

then the liquid spreads on the surface of the solid.
(c) Angle of contact increases with increase in temperature of liquid.
(d) The value of angle of contact for pure water and glass is zero.

A liquid will not wet the surface of a solid, if the angle of contact is

Important Questions on Viscosity and Surface Tension

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