Abhishek DhawanAssistant Manager – Editorial Content
What is the SI Unit?
The abbreviation, ‘SI’ was derived from the French word Système International. The universally accepted metric standard for measurements is the International System of Units (SI). It is based on seven base units and 15 derived units. It can be defined as the prefix of power of 10. It ranges between 10-24 to 1024.
As discussed below, the full form of SI is System international. SI units are used in various areas like technical, scientific, physics, mathematics, etc. SI Units are very important because they help us understand the measurements of the different unit systems.
Base SI Units
The seven base units of SI units are as follows:
| S. No. |
Quantity Name |
SI Unit |
Symbol of SI Unit |
|---|---|---|---|
| 1. |
Length (l) |
Meter |
M |
| 2. |
Mass (M) |
Kilogram |
Kg |
| 3. |
Time (T) |
Second |
S |
| 4. |
Electric Current (I) |
Ampere |
A |
| 5. |
Thermodynamic Temperature (Θ) |
Kelvin |
K |
| 6. |
Amount of substance (N) |
Mole |
Mol |
| 7. |
Luminous Intensity (J) |
Candela |
cd |
The base units are the building blocks of the system. They are further used to derive other SI units. There are 15 derived SI units making a total of 22.
Derived SI Units
The list of 15 derived SI units are as follows:
| S. No. |
Name of the Unit (s) |
SI Unit |
Symbol of SI Unit |
|---|---|---|---|
| 1. |
Force, Weight |
Newton |
N |
| 2. |
Frequency |
Hertz |
Hz |
| 3. |
Electric Charge |
Coulomb |
C |
| 4. |
Electric potential |
Volt |
V |
| 5. |
Inductance |
Henry |
H |
| 6. |
Capacitance |
Farad |
F |
| 7. |
Resistance, Reactance, Impedance |
Ohm |
Ω |
| 8. |
Electrical conductance |
Siemens |
S |
| 9. |
Magnetic flux |
Weber |
Wb |
| 10. |
Magnetic flux density |
Tesla |
T |
| 11. |
Energy, Work, Heat |
Joule |
J |
| 12. |
Power, Radiant flux |
Watt |
W |
| 13. |
Angle |
Radian |
Rad |
| 14. |
Radioactivity |
Becquerel |
Bq |
| 15. |
Luminous flux |
Lumen |
Im |
Apart from base units and derived units, some other units are widely used but didn't make it in the list. They are as follows:
- m/s is the SI unit of velocity
- Tesla is the SI unit of the magnetic field
- Kilogram meter per second (kg. m / s) is the SI unit of momentum
SI Units for Class 11
The chapter 'Units of Measurements' holds a weightage of seven marks. It includes 4 questions in total consisting of two objective type questions of 1 mark each, one very short question of 2 marks, and one short question of 3 marks making a total of seven marks.
Illustrated Examples
Example 1) Write the SI unit of Electric Current.
Answer – The Si unit of Electric Current is Ampere denoted as A
Example 2) Write the SI Unit of Force and Weight.
Answer – The SI Unit of both Force and Weight is the same, i.e., Newton. It is denoted as N.
Example 3) Name the important physical quantities.
Answer – There are seven physical quantities in total, i.e. mass, time, length, electric current, temperature, amount of substance, and light intensity.
FAQs on SI Units
Q: What is the SI unit of Velocity?
Q: What is the SI unit of Radioactivity?
Q: What is the System of Units used for measurements?
-
CGS system
-
MKS system
-
SI system
Q: What are SI derived Units?
Q: What are the advantages of SI Units?
A: The advantages of SI units are as follows:
- It is easy to understand
- It helps students to get an in-depth idea about the topics.
- It helps to retain the concept longer.
News & Updates
Units and Measurement Exam
Student Forum
Anything you would want to ask experts?Popular Courses After 12th
Exams: BHU UET | KUK Entrance Exam | JMI Entrance Exam
Bachelor of Design in Animation (BDes)
Exams: UCEED | NIFT Entrance Exam | NID Entrance Exam
BA LLB (Bachelor of Arts + Bachelor of Laws)
Exams: CLAT | AILET | LSAT India
Bachelor of Journalism & Mass Communication (BJMC)
Exams: LUACMAT | SRMHCAT | GD Goenka Test