To maintain uniformity in measurements all over the world, a common system of units is required. The internationally accepted system of units is called the SI System (International System of Units).
The SI system is based on seven fundamental physical quantities and their corresponding base units. It is used universally in science, engineering, and commerce.
Each fundamental physical quantity has a definite base unit in the SI system.
| Physical Quantity | SI Unit | Symbol |
|---|---|---|
| Length | metre | m |
| Mass | kilogram | kg |
| Time | second | s |
| Electric current | ampere | A |
| Temperature | kelvin | K |
| Amount of substance | mole | mol |
| Luminous intensity | candela | cd |
Derived units are obtained by combining base units using mathematical relations.
Q1. SI system stands for: A) Standard Indian System B) Scientific International System C) System International D) International System of Units Answer: D Q2. SI unit of length is: A) centimetre B) metre C) kilometre D) millimetre Answer: B Q3. Which of the following is NOT a base quantity? A) Mass B) Length C) Speed D) Time Answer: C Q4. SI unit of temperature is: A) degree Celsius B) Fahrenheit C) kelvin D) joule Answer: C Q5. SI unit of electric current is: A) volt B) ampere C) ohm D) coulomb Answer: B
