1. What is the SI unit of surface tension?
A.
N m
B.
N/m
C.
J/m
D.
kg/m
Correct Answer:
N/m
Explanation:
The SI unit of surface tension is newton per metre (N/m), representing force per unit length.
2. Surface tension can also be expressed in SI units as:
A.
J/m²
B.
J m²
C.
N m²
D.
W/m
Correct Answer:
J/m²
Explanation:
Since surface tension is surface energy per unit area, its unit is joule per square metre (J/m²), which is equivalent to N/m.
3. What is the CGS unit of surface tension?
A.
dyne/cm
B.
dyne cm
C.
erg/cm
D.
erg/cm²
Correct Answer:
dyne/cm
Explanation:
In the CGS system, surface tension is measured as force per unit length, so its unit is dyne per centimetre (dyne/cm).
4. Which of the following is equivalent to 1 N/m?
A.
1 J/m²
B.
1 J/m
C.
1 N m
D.
1 Pa/m
Correct Answer:
1 J/m²
Explanation:
A newton per metre is dimensionally equal to a joule per square metre, so 1 N/m = 1 J/m².
5. The dimensional formula of surface tension is:
A.
[M L T⁻²]
B.
[M L⁻¹ T⁻²]
C.
[M T⁻²]
D.
[M L² T⁻²]
Correct Answer:
[M T⁻²]
Explanation:
Surface tension equals force divided by length. Since force has dimensions [M L T⁻²], surface tension has dimensions [M T⁻²].
6. How many dyne per centimetre are equal to 1 N/m?
A.
1 dyne/cm
B.
10 dyne/cm
C.
100 dyne/cm
D.
1000 dyne/cm
Correct Answer:
1000 dyne/cm
Explanation:
Using 1 N = 10⁵ dyne and 1 m = 100 cm, 1 N/m = 10⁵/100 = 1000 dyne/cm.
7. The unit N/m for surface tension indicates:
A.
Force per unit area
B.
Energy per unit volume
C.
Force per unit length
D.
Mass per unit length
Correct Answer:
Force per unit length
Explanation:
Surface tension is defined as the tangential force acting per unit length of a line on the liquid surface.
8. Which unit is not a unit of surface tension?
A.
N/m
B.
J/m²
C.
dyne/cm
D.
N/m²
Correct Answer:
N/m²
Explanation:
N/m² is the SI unit of pressure, whereas surface tension has units of N/m.
9. If the surface tension of a liquid is 0.05 N/m, its value in dyne/cm is:
A.
0.5 dyne/cm
B.
5 dyne/cm
C.
50 dyne/cm
D.
500 dyne/cm
Correct Answer:
50 dyne/cm
Explanation:
Since 1 N/m = 1000 dyne/cm, 0.05 N/m = 0.05 × 1000 = 50 dyne/cm.
10. Which SI unit represents surface energy per unit area and is equivalent to surface tension?
A.
J/m²
B.
J/m³
C.
N/m²
D.
W/m²
Correct Answer:
J/m²
Explanation:
Surface energy divided by area has the unit joule per square metre (J/m²), equivalent to N/m for surface tension.
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