# Short Questions with Answer – Units and Measurement | Physics Class 11

## Important Questions Collection Short Questions with Answer Unit: Units and Measurement Science | Physics Class 11

1. Can we tell the unit of a physical quantity from its dimensions?
Ans: Yes, we can tell the unit of a physical quantity from its dimensions. For example, if a physical quantity has the dimension [M0LT-1] then its SI-unit will be ms-1.

2. Can dimensional analysis tell you that a physical relation is completely right?
Ans: The numerical factor in relation cannot be determined. Therefore Dimensional analysis cannot tell us that a physical relation is completely right.

3. What is the importance of base units?
Ans: There are seven base units in SI-units and all physical quantities can be expressed in term of these base units.

4. Do all the constants carry dimension?
Ans: No, all the constants do not carry dimensions but some constants carry dimensions. For example G is a constant which has a dimension.

5. Which physical quantities have the same dimensions of [ML-1T-2]?
Ans: Pressure, Stress and Young’s modulus have the same dimension of [ML-1T-2].

6. Can a physical quantity have unit but is dimensionless?
Ans: Yes, it is possible to have unit but no dimension. For example angle has no dimension but has the unit of radian.

7. What are characteristics of a physical standard?
Ans: A physical standard must have following characteristics:

(i) Invariability
(ii) Accessibility
(iii) Indestructibility, and
(iv) Reproducibility

8. Does the measurement of a physical quantity depend upon the system of units used?
Ans: It doesn’t depend on the system of units. There is only change in the numerical value of the physical quantity.

9. Do you think that a definition of a physical quantity for which no direct method of measurement is known or given has a physical meaning?
Ans: Yes, the measurement may be made by indirect method.

10. Can you suggest a way to measure length along a curved line?
Ans: The length along a curved line may be measured by the technique of trajectory or by measuring the length of string by placing t on the curved line.

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