🔍 Doubt Destroyer: Units, Dimensions, and Least Count
1️⃣ Understanding Units
- Physical Quantity: Anything that can be measured (e.g. length, time).
- Unit: A standard quantity used to express a physical quantity.
- Types of Units:
- Fundamental Units: Cannot be derived from other units (e.g. metre, kilogram, second).
- Derived Units: Formed by combining fundamental units (e.g. m/s, N, J).
- SI System: International System of Units — the standard for scientific measurement.
2️⃣ Dimensions Demystified
Dimensions express a physical quantity in terms of base quantities like mass (M), length (L), and time (T).
- Example: Speed has dimensions of [L T-1]
- Force: [M L T-2]
🧠 Why are dimensions important?
– To check if equations are dimensionally correct
– To derive formulas
– To convert units
– To check if equations are dimensionally correct
– To derive formulas
– To convert units
3️⃣ Least Count Explained
Least Count is the smallest value that can be measured by an instrument.
- Ruler: Least count = 1 mm or 0.1 cm
- Vernier Calliper: Least count = 0.01 cm
- Screw Gauge: Least count = 0.001 cm
✨ Concept Tip: Smaller least count = Higher accuracy.