1. Surface tension of a liquid is defined as the force acting per unit length on its free surface in which direction?
A.
Perpendicular to the surface
B.
Tangentially to the surface
C.
Vertically downward only
D.
Randomly in all directions
Correct Answer:
Tangentially to the surface
Explanation:
Surface tension is the tangential force acting per unit length along the free surface of a liquid.
2. What is the SI unit of surface tension?
A.
N m
B.
N/m
C.
J/m
D.
Pa/m
Correct Answer:
N/m
Explanation:
Since surface tension is force per unit length, its SI unit is newton per metre, written as N/m.
3. If F is the force acting along a liquid surface and l is the length over which it acts, surface tension T is given by:
A.
T = F l
B.
T = F/l
C.
T = l/F
D.
T = F + l
Correct Answer:
T = F/l
Explanation:
Surface tension is defined as force per unit length, so T equals F divided by l.
4. Surface tension acts along which part of a liquid surface?
A.
Along its surface
B.
Only at its bottom
C.
Only at its centre
D.
Inside the liquid in every direction
Correct Answer:
Along its surface
Explanation:
Surface tension is associated with the free surface and acts tangentially along that surface.
5. Which physical quantity is represented by force per unit length at the surface of a liquid?
A.
Pressure
B.
Density
C.
Surface tension
D.
Viscosity
Correct Answer:
Surface tension
Explanation:
Surface tension is defined as the force acting per unit length along the liquid surface.
6. A liquid surface has a force of 0.2 N acting along a length of 0.1 m. What is its surface tension?
A.
0.02 N/m
B.
0.2 N/m
C.
2 N/m
D.
20 N/m
Correct Answer:
2 N/m
Explanation:
Using T = F/l, the surface tension is 0.2 N divided by 0.1 m, which equals 2 N/m.
7. The dimensional formula of surface tension is the same as that of:
A.
Force
B.
Energy per unit area
C.
Pressure
D.
Momentum
Correct Answer:
Energy per unit area
Explanation:
Surface tension has unit N/m, which is equivalent to J/m², the unit of energy per unit area.
8. Which statement correctly describes surface tension?
A.
It is force per unit area acting normally on a surface
B.
It is force per unit length acting tangentially on a liquid surface
C.
It is mass per unit volume of a liquid
D.
It is energy per unit volume of a liquid
Correct Answer:
It is force per unit length acting tangentially on a liquid surface
Explanation:
The definition of surface tension is tangential force per unit length acting at the free surface of a liquid.
9. If the force acting along a liquid surface is doubled while the length remains unchanged, the surface tension becomes:
A.
Half
B.
Unchanged
C.
Twice
D.
Four times
Correct Answer:
Twice
Explanation:
From T = F/l, with length constant, surface tension is directly proportional to the force.
10. Surface tension is a property associated mainly with which part of a liquid?
A.
Its free surface
B.
Its deepest layer only
C.
Its entire volume equally
D.
Its container only
Correct Answer:
Its free surface
Explanation:
Surface tension describes the tangential force per unit length acting at the free surface of a liquid.
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