Dear Aspirants, in every competitive exam **Units of Measurement,** are the most important part of General Science.so here we provide detail information about **Units of Measurement **which helps to Aspirants for SSC, Railway NTPC, Group-D, and State PSU examination.

A **unit of measurement** is a definite magnitude of a quantity, that is used as a standard for measurement of the same kind of quantity. Many quantities can be expressed as a multiple of the unit of measurement.

To measure any quantity, a definite and a substantial amount of that quantity, is assumed to be standard Which is called a unit of the quantity and when any given quantity is measured in the terms of this unit, the process is called *measurement*.

There are usually two types of units

(a) Fundamental Units

(b) Derived Units

**(a) Fundamental or Base Units: **

- If a physical quantity is expressed in terms of units that are used as standards and these standards are independent of each other, then these units are called Fundamental or Base Units.
- There are Seven Fundamental Units.

(b) **Derived Units:**

- If a physical quantity is expressed in terms of two or more fundamental units these units are called Derived Units.
- These units have no independent existence like fundamental units.

Example –Force, work, power, etc.

**System of Units**

Usually, physical quantities are measured in four systems of units

**CGS System**(Centimeter Gram Second System):

In this system of units Length, Mass and Time are measured in Centimeter, Cram and Second respectively. CGS system is also called Metric or French

System of Units.

2.**MKS System** (Meter Kilogram Second System):

In this system of units Length, Mass and Time are measured in Meter, Kilogram and Second.

**SI System**(International System of Units) :

The SI System of Units was adopted and accepted on the basis of a comprehensive consensus. In fact, the SI system is an extended and modified

form of the MKS System.

**FPS System**(Foot Pound Second System):

In this System of units Length, Mass and Time are measured in Foot, Pound and Second. FPS system is also called the British System of Units.

There are Seven Fundamental Units and two Supplementary Units in the SI system.

__Fundamental units__

SI No. | Quantity | Unit |
---|---|---|

1 | Length | Metre |

2 | Mass | kilogram |

3 | Time | Second |

4 | Temperature | Kelvin |

5 | Electric Current | Ampere |

6 | Luminous Intensity | Candela |

7 | Amount of Substance | Mole |

__Supplementary Units__

- Plane Angle- Radian
- Solid Angle- Steradian

**Important Physical Quantities and Their Units**

SI No. | Quantity | Unit |
---|---|---|

1 | Length | Meter |

2 | Time | Second |

3 | Mass | kilogram |

4 | Area | Square meter |

5 | Volume | Cubic meter |

6 | Speed | Meter/second |

7 | Velocity | Meter/second |

8 | Acceleration | Meter/second square |

10 | Density | Kilogram/meter cube |

11 | Momentum | Kilogram x meter/second |

12 | Work | Joule |

13 | Energy | Joule |

14 | Force | Newton |

15 | Torque | Newton x meter |

16 | Couple | Newton x meter |

17 | Pressure | Pascal or Newton/square meter |

18 | Frequency | Hertz |

19 | Power | watt |

20 | Weight | Newton or Kilogram |

21 | Impulse | Newton x Second |

22 | Angular Velocity | Radian /Second |

23 | Viscosity | Poise |

24 | Surface tension | Newton/ Meter |

25 | Temperature | Kelvin |

26 | Absolute temperature | Kelvin |

27 | Electric current | Ampere |

28 | Electromotive force | Volt |

29 | Electrical conductivity | Ohm/meter |

30 | Electric energy | Kilo watt-hour |

31 | Electric power | Kilowatt or watt |

32 | Magnetic intensity | Orsted |

33 | Charge | Coulomb |

34 | Ship | Knot |

35 | Aeroplane | Mach |

36 | Relative density | No unit |

37 | Gravity (g) | Meter/second square |

38 | Gravitation (G) | Newton x Meter^{2}/Kg^{2} |

39 | Magnetic induction | Gauss |

40 | Luminous flux | Candela |

41 | Intensity of sound | Decibel |

42 | Power of lens | Diopter |

43 | Depth of sea | Fathom |

44 | Wavelength | Meter |

45 | Angular acceleration | rad/Second square |

46 | Centripetal force | Newton |

47 | Stress | newton /meter square |

48 | Strain | No unit |

49 | Specific gravity | No unit |

50 | Specific Heat capacity | Joule/Kg K |

51 | Gold, Diamond | Carat |

52 | Astronomical Distance | Light year |

53 | Heat | Joule, Calorie |

54 | Latent heat | CaIorie / gm |

55 | Specific heat | cal/gm X C^{0} |

56 | Resistance | Ohm |

57 | Specific resistance | Ohm x cm |

58 | Potential difference | volt |

59 | Capacitance | Farad |

60 | Conductance | Mho |

61 | Supersonic motion | Mach |

62 | Inductance | Henry |

63 | Magnetic flux | Weber |

64 | Magnetic flux density | Tesla |

65 | Magnetic field Stress | ampere/meter |

66 | Entropy | Joule/ Kelvin |

67 | Thermal conductivity | watt / meter |

68 | Nuclear energy | Fermi |

69 | Plane Angle | Radian |

70 | Solid Angle | Steradian |

71 | Luminous Intensity | Candela or Lumen |

72 | Amount of Substance | Mole |

73 | Linear Momentum | Newton/sec |

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In this article, cover the important list of Quantities and their *Units of Measurement* which are exam-oriented. If you have any doubt please leave a comment in the comment box.