# Important SI Units in Physics

In physics, there are various terms and quantities. The different quantities in physics can be expressed in various units. Now, the SI units are used to represent the base and derived quantities. There are several SI units in physics which are used presently. The SI unit list of some of the important quantities in physics are given below.

What is SI Unit?

The term SI unit is the abbreviation of the French word Système International. SI or the International System of Units is now the most widely used system of measurement. The SI units have been in existence since 1960. This has replaced the varying measurement units and has made it easier to express the units universally.

SI Units List for Physics

There are several SI units used in physics that are used to express the different quantities. The quantities can be classified into two groups i.e. base units and derived units.

• SI Base Units

These are the fundamental units and are considered as the building blocks of the system. All the other units are derived from the SI Base units. One of the examples is that the SI unit of mass is kilogram. This is often confused with grams.

SI Base Units List:

There are 7 SI base units. The seven units along with their SI unit and symbol are given below:

Sl. No.

Name of the Quantity

SI Unit

SI Unit Symbol

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

It should be noted that these 7 units are assumed to be mutually independent and hence are called base units. The SI units of measurement for both base and derived units are given below.

• SI Derived Units

The derived units are unlimited as they are formed by different operations on the base units. For derived units, the dimensions are expressed in terms of the dimensions of the base units. The derived units might also be expressed with the combination of base and derived units.

SI Derived Units List:

There are several derived units in physics. Some of the most widely used SI derived units in physics are given below.

Sl. No

Unit(s) Name

SI Unit

SI Unit Symbol

Expressed in SI Base Unit

Expressed in other SI units

1.

Force, Weight

Newton

N

kg⋅m⋅s-2

2.

Frequency

Hertz

Hz

s-1

3.

Electric charge

Coulomb

C

s⋅A

4.

Electric potential (Voltage)

Volt

V

kg.m2.s-3.A-1

W/A

5.

Inductance

Henry

H

kg.m2.s-2.A-2

Wb/A

6.

Capacitance

F

kg−1.m−2.s4.A2

C/V

7.

Resistance, Impedance, Reactance

Ohm

Ω

kg.m2.s−3.A−2

V/A

8.

Electrical conductance

Siemens

S

kg−1.m−2.s3.A2

Ω−1

9.

Magnetic flux

Weber

Wb

kg.m2.s−2.A−1

V⋅s

10.

Magnetic flux density

Tesla

T

kg.s−2.A−1

Wb/m2

11.

Energy, Work, Heat

Joule

J

kg.m2.s−2

N⋅m = Pa⋅m3

12.

Watt

W

kg.m2.s−3

J/s

13.

Angle

m.m−1

14.

Becquerel

Bq

s-1

15.

Luminous flux

Lumen

lm

cd

cd⋅sr

These were a few widely used units along with their SI units. Apart from these units, there are certain additional units that are commonly seen in physics. Some of such units are:

• The SI unit of momentum (P) is kilogram meter per second (kgm/s)
• The SI unit of magnetic field (B) is tesla
• The SI unit of heat is unit joule
• The SI unit of velocity is m/s

Students are suggested to be thorough with these aforementioned important physics SI units lists. In the exam, it is important to write the SI unit corresponding to the quantity as an answer is considered incomplete without its unit.

For more assistance on physics, keep visiting BYJU’S. At BYJU’S, students are also provided with several question papers, notes and important questions to help them learn physics more efficiently and help them prepare for the exams in a better way.