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Fundamental Quantities in Physics

7 Fundamental Quantities, their Symbols and SI Units.

Here is a brief table of fundamental quantities:

Fundamental QuantitySymbolUnit
LengthLMeter (m)
MassMKilogram (kg)
TimeTSecond (s)
Electric CurrentIAmpere (A)
TemperatureθKelvin (K)
Amount of SubstanceNMole (mol)
Luminous IntensityJCandela (cd)
Fundamental Quantities

These are the seven fundamental physical quantities used as the base for deriving other units in the International System of Units (SI).

What are Fundamental Quantities in Physics?

Fundamental quantities in Physics are basic quantities that provide the basic units of measurement. We can equally define fundamental quantities in Physics as fundamental units that are the accepted standard units or measures in which measurement is made. Finally, fundamental quantities are quantities that do not depend on other quantities.

Physics, as a fundamental science, seeks to understand the laws and principles governing the natural world. To accomplish this, physicists rely on the use of various measurements and quantities. Among these, fundamental quantities play a crucial role. In this article, we will explore the concept of fundamental quantities in physics and their significance in scientific investigations.

Frequently Used Fundamental Units

The fundamental units we frequently used are as follows:

  1. Meter as the unit of Length
  2. Kilogram as the unit of mass
  3. Second as a unit of time
  4. Ampere as the unit of current
  5. Kelvin as the unit of temperature
  6. Candela as the unit of luminous intensity
  7. Weber as a unit of magnetic flux
  8. Mole is for the amount of substance


Mass is one of the fundamental quantities in physics. It represents the amount of matter an object contains. In the International System of Units (SI), mass is measured in kilograms (kg). It is also a fundamental property of objects and is independent of their location or environment.

In physics, the mass has a profound impact on various phenomena. For instance, it determines the gravitational force an object experiences and affects its inertia. Objects with larger masses require more force to accelerate or decelerate, this is according to Newton’s second law of motion. Furthermore, mass is a key factor in understanding concepts like energy, momentum, and density.

In our everyday lives, we encounter the concept of mass regularly. Whether it’s weighing groceries at the supermarket or discussing the mass of celestial bodies. Therefore, the understanding of mass is essential for both scientific and practical purposes.


Length is another fundamental quantity that holds immense significance in physics. It refers to the measurement of an object’s extension in one dimension. The SI unit for length is the meter (m). Length is a fundamental parameter for describing the size, position, and motion of objects.

The concept of length finds applications in various scientific disciplines. In physics, it plays a vital role in determining the displacement, velocity, and acceleration of objects. It is also crucial in fields such as optics, where we measure the wavelength of light in terms of length.

Therefore, from measuring the height of a building to characterizing the size of subatomic particles, length serves as a fundamental reference for quantifying the physical world.


Time is a fundamental quantity that governs the progression of events. It is the measurement of the sequence in which events occur. In physics, time is measured in seconds (s). Time allows us to analyze the motion, change, and duration of phenomena.

The concept of time is central to many physical theories and laws. It plays a vital role in understanding concepts such as velocity, acceleration, and frequency. The laws of motion formulated by Newton and the principles of relativity developed by Einstein heavily rely on the notion of time.

Time measurements and their applications are ubiquitous in our daily lives. From setting alarms to coordinating schedules, timekeeping is essential for efficient organization and planning. Moreover, precise time measurements are very important in fields such as navigation, astronomy, and telecommunications.

Electric Current

Electric current is a fundamental quantity in physics that describes the flow of electric charge. It is measured in amperes (A) and represents the rate at which electric charges move through a conductor. Additionally, electric current plays a vital role in understanding electrical circuits, electromagnetism, and the operation of various electrical devices.

In physics and technology, electric current finds numerous practical applications. It powers our homes, provides energy for electronic devices, and drives electric motors. Therefore, from the generation of electricity to its utilization, a comprehensive understanding of electric current is crucial for advancements in electrical engineering and technology.


Temperature is a fundamental physical quantity that measures the hotness or coldness of an object. It quantifies the average kinetic energy of the particles within a system. The SI unit for temperature is the Kelvin (K), although Celsius (°C) and Fahrenheit (°F) scales are commonly used.

Temperature plays a critical role in various branches of physics, particularly in thermodynamics. It helps in understanding heat transfer, phase transitions, and the behaviour of gases. Additionally, temperature measurements have significant implications in meteorology, climate science, and materials science.

Furthermore, different temperature scales, such as the Kelvin scale used in scientific research and the Celsius scale for everyday applications, allow us to quantify and compare thermal conditions in various contexts.

Amount of Substance

The amount of substance, also known as the chemical amount, is a fundamental quantity that measures the quantity of a substance in terms of its elementary entities, such as atoms or molecules. The SI unit for the amount of substance is the mole (mol).

In both chemistry and physics, the amount of substance is crucial for studying the behaviour of substances, chemical reactions, and the properties of materials. It enables scientists to determine stoichiometry, and molar mass, and perform quantitative analyses. The concept of the mole provides a standardized and universal approach to quantifying substances, facilitating accurate measurements and comparisons in scientific research.

Luminous Intensity

Luminous intensity is a fundamental quantity that measures the amount of light emitted, transmitted, or received per unit solid angle. It is measured in candela (cd). Luminous intensity is essential in the field of optics, where it helps quantify the brightness of light sources and the effectiveness of illumination.

Understanding luminous intensity is crucial for various applications, including lighting design, photography, and display technologies. It enables scientists and engineers to develop efficient lighting solutions, optimize visual perception, and create captivating visual displays.


In conclusion, fundamental quantities in physics are essential building blocks for understanding and quantifying the physical world. Mass, length, time, electric current, temperature, amount of substance, and luminous intensity form the foundation upon which scientific investigations and technological advancements are based. By comprehending these fundamental quantities, physicists and researchers gain insights into the laws of nature and develop innovative solutions that shape our understanding of the universe.

Fundamental Quantities in Physics
Fundamental Quantities in Physics


  1. What are the fundamental quantities in physics? The fundamental quantities in physics are mass, length, time, electric current, temperature, amount of substance, and luminous intensity.
  2. How are fundamental quantities measured? Fundamental quantities are measured using standardized units such as kilograms, meters, seconds, amperes, kelvin, moles, and candelas.
  3. Can fundamental quantities change over time? Fundamental quantities themselves do not change over time. They are intrinsic properties of objects and phenomena. However, our understanding of these quantities and their measurement techniques may evolve with scientific advancements.
  4. Are fundamental quantities the same in all countries? Yes, fundamental quantities are universally defined and recognized. The International System of Units (SI) provides standardized units (SI units) for fundamental quantities that are accepted and used worldwide.
  5. Why are fundamental quantities important in scientific research? Fundamental quantities serve as the basis for scientific measurements and calculations. They provide a common language and framework for scientists to communicate and compare their findings. Understanding fundamental quantities is crucial for conducting accurate experiments, formulating scientific theories, and making meaningful contributions to various fields of research.

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