Introduction
Physics is the science of measurement, and every physical quantity must be expressed quantitatively. Units and Dimensions form the foundation of Physics, helping us measure, compare, and understand physical quantities accurately. In this chapter, we study different systems of units, fundamental and derived quantities, and the concept of dimensions, which are essential for analyzing physical laws and formulas.
Understanding units and dimensions is crucial because it allows us to check the correctness of equations, convert units from one system to another, and simplify complex physical relationships.
Overview of the Topic
- Physical Quantities are classified into fundamental and derived quantities
- Units are standard references used to measure physical quantities
- SI System of Units is the internationally accepted system
- Dimensions represent the powers to which fundamental quantities are raised
- Dimensional Analysis helps in:
- Checking dimensional consistency of equations
- Deriving relations between physical quantities
- Converting units from one system to another
Relevance for NDA & CDS 1 2026 Exam
- Questions from Units and Dimensions are frequently asked in NDA & CDS Physics
- Usually 1–2 direct or conceptual questions appear in the exam
- Topics are scoring and time-saving if concepts are clear
- Strong foundation here helps in understanding later chapters like Mechanics, Thermodynamics, and Waves
Conclusion
Units and Dimensions act as the backbone of Physics and are the first step toward mastering the subject for competitive exams. A clear understanding of this chapter ensures accuracy in problem-solving and boosts confidence in tackling numerical questions. For NDA & CDS 1 2026, this topic offers an excellent opportunity to score easy and guaranteed marks with proper conceptual clarity and practice.
