Physical constants are a set of fundamental invariant quantities which are mainly observed in nature and generally physical science, we use them in the basic theoretical equations in order to check the correctness of the physical equations. There are many important constants in physics that are very essential to make the theories based on them that are relevant to daily life such as the speed of light, the charge of an electron, etc.

## Types of Constants In Physics

**Speed of Light**

Speed of light is a universal constant of nature. The value of the speed of light does not depend on any particular experiments. The speed of light in a vacuum is represented by c and the value of c is \(3\times 10^{8}\) m/s. In electromagnetic theory and theory of relativity, the universal constant speed of light is used. The speed of light generally relates energy to mass through the equation \(E=mc^{2}\).

**Charge of Electron**

The charge of an electron is mainly a fundamental property of a particle that is present physically in nature. The symbol of the charge of an electron is \(\epsilon\). The charge of an electron is the smallest unit of electric charge which is found free in nature. The numerical value of the electric charge is required in many fields such as physics, chemistry. It is useful for calculating the mass of an element or compound.

**Planck’s Constant**

Planck’s constant is one of the most important properties of a particle in the equations of quantum mechanics. The symbol of Planck’s constant is h. Planck’s constant mainly relates the energy of a photon to its frequency.

**Universal Gravitational Constant**

The universal gravitational constant is denoted by G. The universal gravitational constant mainly relates the attractive force due to gravity between the two bodies to their masses and the distance between the two bodies. It is very difficult to measure the value of the universal gravitational constant by any experiment. The value of the gravitational constant varies with time.

**Boltzmann Constant**

The symbol of the Boltzmann constant is k. It is mainly useful in quantum mechanics. The value of Boltzmann constant is \(1.380649\times 10^{-23}\) joule per Kelvin. Boltzmann constant mainly uses for measuring the amount of energy.

**Permeability of Free Space**

The permeability of free space is a physical constant that is useful in electromagnetism. The symbol of permeability of free space is \(\mu _{0}\). The exact value of permeability of free space is \(4\Pi\times 10^{-7}\) Newton per ampere squared. The permeability of free space is also related to the speed of light. This constant gives us an idea about how strong the force is between two electric currents.

**FAQs about Constant in Physics**

Q.1 What is the need for constant in physics?

Answer: Physical constants are useful in physics to check the correctness of the physical equations which are relevant to nature.

Q.2: Name some fundamental constants in physics.

Answer: The fundamental constants in physics are Velocity of light, the charge of an electron, Planck’s constant, fine structure constant, the permeability of free space, the mass of an electron, Bohr radius, etc.

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