International System of Units

Introduction:

It is necessary for all CBSE senior secondary appearing students to have a strong base in class 11th only. It all starts by scoring high in the CBSE 11th class with the help of Unacademy notes and lectures. Our experienced faculty has more than decades of experience in offering the best study material and online learning experience through websites and apps. When it comes to physics, the international system of units forms a base. These are the internationally accepted units for measurements and come in two forms- base and derived. The multiple base and derived units are ideal to perform all calculations and measurements using international standards.

Units in Physics

There are multiple systems of units used in physics. Some of the popular ones are SI units, MKS system, FPS system, and CGS systems. Many times students feel confused about the meaning of the SI unit? The MKS system uses meters, kilogram, and second as the base units. The FPS system is the foot, pound, and the second system for the units of length, weight, and time respectively. The CGS system is the centimeter, gram, second for the units of length, weight, and time respectively.  The SI units are used internationally and define seven base units. Let us know more details about these units.

What is the international system of units?

The international system of units is a universally used standard for multiple measurements. Hence, all these units play a crucial role in multiple scientific and development research globally. There are seven base units that can define 22 derived units. The base units are mutually independent while the derived units are the combinations of bases. All these units can be represented as fractional quantities or as the standard multiples. The prefix multipliers range in the powers of 10 from 10 raised to power -24 to 24.

What is a SI units list?

SI is an abbreviation of the French word “Systeme International.” This standard system avoids any issues of confusion while considering multiple quantities in scientific and non-scientific research. The top seven SI units are:

Sr. No.	Name of unit	SI unit
1	Length	meter (m)
2	Mass	Kilogram (kg)
3	Time	Second (s)
4	Electric current	Ampere (A)
5	Thermodynamic temperature	Kelvin (K)
6	Amount of substance	Mole (mol)
7	Luminous Intensity	Candela (cd)

What is the SI base units list?

The SI base units form the base of any system and hence called the fundamental units. There are seven SI base units that are mutually independent of each other. These units are:

Sr. No.	Name of unit	SI unit	Definition
1	Length	meter (m)	It is defined by taking the fixed value of the speed of light in vacuum.
2	Mass	Kilogram (kg)	It is defined by taking the fixed value of the Planck constant.
3	Time	Second (s)	It is defined by taking the fixed value of the Cesium frequency.
4	Electric current	Ampere (A)	It is defined by taking the fixed value of the elementary charge.
5	Thermodynamic temperature	Kelvin (K)	It is defined by taking the fixed value of Boltzmann constant, k= 1.380649*(10)-23
6	Amount of substance	Mole (mol)	It is defined by the fixed value of the Avogadro constant NA. One mole contains 6.02214076*(10)23 elementary entities.
7	Luminous Intensity	Candela (cd)	It is defined by the fixed value of the luminous efficacy

What is the SI derived units list?

The units that are derived from the main seven SI units are called derived units of SI. The dimensions of these units are represented in the dimensions of the base units only. These can be represented as a combination of base and derived both. Some of the widely used derived SI units include:

Sr. No.	Name of unit	SI unit	SI unit symbol	Expression in base SI unit
1	Frequency	Hertz	Hz	s-1
2	Electric Potential (Voltage)	Volt	V	kg.m2.s-3.A-1
3	Capacitance	Farad	F	kg−1.m−2.s4.A2
4	Electrical conductance	Siemens	S	kg−1.m−2.s3.A2
5	Magnetic flux	Weber	Wb	kg.m2.s−2.A−1
6	Magnetic flux density	Tesla	T	kg.s−2.A−1
7	Power, Radiant flux	Watt	W	kg.m2.s−3
8	Luminous flux	Lumen	lm	cd
9	Radioactivity	Becquerel	Bq	s-1
10	Force, Weight	Newton	N	kg⋅m⋅s-2
11	Electric charge	Coulomb	C	s⋅A
12	Inductance	Henry	H	kg.m2.s-2.A-2
13	Resistance, Impedance, Reactance	Ohm	Ω	kg.m2.s−3.A−2
14	Energy, Work, Heat	Joule	J	kg.m2.s−2
15	Angle	Radian	rad	m−1

Benefits of the international system of units

The main advantages of these SI units include:

• It helps in quick learning for students as all units are provided in points that facilitate quick retaining
• It helps students solve different questions related to the SI and CGS units that are quite common in physics syllabus
• The units and the in-depth knowledge about them help understand deeply about the respective topics
• It helps students learn the units in an interactive manner and can be easily understood to help students gain physics knowledge effortlessly

Conclusion:

So, it is easy to understand all about the international system of units from easy and detailed Unacademy notes. Starting from the clear definition of these units and to the basic difference between the base and derived units, it becomes easy to understand all about this physics topic. The eagle’s eye view of the metric system, from the experienced faculty of Unacademy, ensures that it creates a smooth base for the class 11th students. The SI units are further crucial to do all different measurements and understand their applications in physics. The different advantages of the SI system make it an internationally accredited system for all calculations.