Author Panel
Units
The chosen standard used for measuring a physical quantity is called unit.
System of Units
Few internationally accepted systems are
- CGS system
- FPS System
- SI Units.
SI Base Units
There are 7 Base Units in SI system. They are –
| Base Quantity | Unit | Symbol |
| Length | Metre | m |
| Mass | Kilogram | kg |
| Time | Second | s |
| Electric Current | Ampere | A |
| Thermodynamic temperature | Kelvin | K |
| Amount of substance | Mole | mol |
| Luminous intensity | Candela | cd |
SI Supplementary Units
| Supplementary Quantity | Unit | Symbol |
| Plane angle | Radian | rad |
| Solid angle | Steradian | Sr |
Standard Units
| viscocity | pascal second |
| Power | dioptre |
| Inductance | henry |
| Loudness | phon |
| Magnetic inductance | tesla |
| Magnetic flux | weber |
| Electric charge | coulomb |
Important Prefixes to Units
- Tera (T) ➟ 1012
- Giga (G) ➟ 109
- Mega (M) ➟ 106
- kilo (K) ➟ 103
- hecto (h) ➟ 102
- deka (da) ➟ 10
- deci (d) ➟ 10–1
- centi (C) ➟ 10–2
- mili (m) ➟ 10–3
- Micro (µ) ➟ 10–6
- nano (n) ➟ 10–9
- Pilo (P) ➟ 10–12
- Femp (f) ➟ 10–15
- atto (a) ➟ 10–18
