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NCERT Solutions for Class 11 Physics Ch-1: Units and Measurements
NCERT Solutions for Class 11 Physics Chapter 1 Units and Measurements covers the fundamental and derived physical quantities, the International System of Units (SI), dimensional analysis, and the treatment of errors and significant figures in measurement.
Overview of Topics & Subtopics
Important Questions and Answers
Q1: What are the seven fundamental (base) quantities in the SI system?
Answer: The seven fundamental quantities in the SI system are: length (metre), mass (kilogram), time (second), electric current (ampere), thermodynamic temperature (kelvin), amount of substance (mole), and luminous intensity (candela).
Q2: What is meant by the 'dimensions' of a physical quantity?
Answer: The dimensions of a physical quantity are the powers to which the fundamental units (mass M, length L, time T, etc.) must be raised to represent that quantity. For example, the dimensional formula of speed is [M0L1T-1].
Q3: State the principle of homogeneity of dimensions and its use.
Answer: The principle of homogeneity states that the dimensions of all terms on both sides of a valid physical equation must be identical. It is used to check the correctness of physical equations and to derive relationships between physical quantities.
Q4: What are significant figures, and why are they important in measurement?
Answer: Significant figures are the digits in a measured value that are known reliably plus one estimated digit. They are important because they indicate the precision of a measurement and ensure that calculated results do not falsely imply greater accuracy than the original measurements allow.
Q5: Name the two main types of errors in measurement.
Answer: The two main types of errors are systematic errors (arising from faults in the experimental setup, instrument calibration, or procedure, which tend to occur in one direction) and random errors (arising from unpredictable fluctuations in conditions, which occur irregularly in both directions).
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