[Physics Class Notes] on Constants in Physics Pdf for Exam

The significance of constants in Physics is that throughout all of the formulations of the basic theories of Physics and the application to the real world, physical constants appear as fundamental invariant quantities, and they have specific and universally used symbols, that are of such importance that they must be known to as high an accuracy as is possible.

The physical constant also called the fundamental constant or the universal constant is a physical quantity that is believed to be universal in nature and has a constant value at all times.

Fundamental Constants in Physics

Speed of light in vacuum = c

Planck’s constant = h

The electric constant = ε0

The elementary charge = e

Constant Value in Physics

In physics, we deal with various dimensions, and to set the dimensions of an entity, the time length of an event, or the density of the fluid we need to compare them with other entities,  we use as a reference. These entities are the constants of physics, such as the speed of light (c), the charge of the electron(e) or mass (mp) of a proton, Rydberg constant, and so on.

For example, the value of Avogadro’s number is 6.02214 x 10²³ mol⁻¹ remains the same everywhere.

Important Physical Constants

There are various fundamental constants to describe the universe as completely as possible; a few are listed below:

Table: List of All Constants in Physics

S.No

Name

Formula

Value

1.

Von Klitzing constant

Rk = 2πh/e²

25812.80745…Ω

2.

Curie constant

C = X (T – θ)

1.3047 K * A/(T * m)

3.

Fine-structure constant

α = e²/2hcε0

0.007297351

4.

Compton wavelength

λ = h/mc

In meter: 2.42 x 10⁻¹²m 

In Angstrom = 0.242 Å 

5.

Impedance of free space

Z0 = 1/ε0c0

376.730…Ω

6.

Bohr radius 

a0  = 4πε0 h²/e²mₑ 

0.0529 m

7.

Faraday constant

F = eNA

96,485 C/mol

8.

Vacuum electric permittivity

ε0 = 1/μ0

8.854 x 10⁻¹² F.m

9.

Stefan–Boltzmann constant

σ = π²k⁴/60h³c²

5.67 x 10⁻⁸Js⁻¹m⁻²K⁻⁴

10.

Thomson cross section

σe = (8π/3)re²

6.6524587321 x 10⁻29

11.

Vacuum magnetic permeability

μ0

1.25663706212(19)x10⁻⁶N. A⁻²

All physics constants

Table: All Constant Values in Physics 

S.No.

Name

Symbol

Formula

Value

1.

Reduced Planck constant

ħ

h/2π

1.05457 x 10⁻³⁴ J.s

2.

Deuteron mass

mD 

—                         

2.013553212745(40) u

1875.612928(12)MeV

1.67377 x 10⁻²⁷ kg or 

1.67377 x 10⁻²⁴g

3.

Josephson constant

KJ

2e/h

483597.84… x 10⁸ Hz./V

4.

Rydberg constant

R

α2. mec/2h

10.973731.56(12)m⁻¹

5.

Proton mass

mp

1.672621898(21) x 10⁻²⁷ kg

1.672621898(21) x 10⁻²⁴ kg

1.007276466879(91)u

938.2720813(58) MeV/c²

6.

Neutron mass

mn

1.674927471(21) x 10⁻²⁷ kg

1.674927471(21) x 10⁻²⁴ g

1.00866491588(49) u

939.5654133(58) MeV/c²

7.

Electron mass

me

9.10938356(11) x 10⁻³¹ kg

9.10938356(11) x 10⁻²⁸ g

5.48579909070(16) amu

0.5109989461(31)MeV/c²

8.

Boltzmann’s constant

Kb

1.380649 x 10⁻²³ J/K

1.380649 x 10⁻16erg/K

9.

Rest mass o
f the electron

me

2Rh/cα2

0.51099895000(15) Mev

11.

Gas constant

R

8.3144598(48) J/K mol

8.3144598(48) x 10³ amu.m²/s²K

8.3144598(48) x 10⁻² L.bar/K mol

8.3144598(48) m³ .Pa/K.mol

62.363577(36) L.T or/K.mol

1.9872036(11) x 10⁻³ Kcal/K.mol

8.2057338(47)x10⁻⁵m³.atm/K.mol

0.082057338(47) L.atm/K.mol

12.

Alpha particle mass

mα

6.644657230(82) x ⁻²⁷ kg

4.001506179127(63) u

3.727379378(23) GeV/c² 

 

Famous Constants in Physics

There are so many constants besides those I mentioned above, but some constants in physics are recognized widely.

Constant values in physics that are most popular among all the physical constants are as follows:

()

S.No.

Name

Symbol

Value

1.

Speed of the light in vacuum

c

3 x 10⁸ m/s 

2.

Planck’s constant

h

6.62607015 x 10⁻³⁴ J.s

3.

Gravitational constant

G

6.673 x 10⁻¹¹ Nm²/kg²

4.

Elementary charge

e, qe (charge of a proton)

1.602176634 x 10⁻¹⁹ C

5.

Electric constant

ε0

8.9875517923(14) x 10⁹ kg.m³.s⁻⁴.A⁻²

The physical constant is a complex concept that is taught in class 11 physics. This is based on the curriculum set by the Central Board of secondary education and physical constants or Constance of Physics holds a significant weightage in the examination and therefore are extremely important to understand. The concept of physical constants can be studied in depth in the study notes that I provided by Vedanta, these notes are repaired by Vedanta’s export research team who are well-versed in research and curating study notes for students, ’s exports have extensive experience and have done thorough research in the duration of these study notes. The notes provided by Vedanta are based on the latest CBSE curriculum and are therefore up to date.

Physical constants are known by different titles such as fundamental constant, universal constant, Constance of physics. It is extremely important to have an accurate evaluation of the physical constants as their accuracy will help to check how up to the mark the theories are, as they form the basis of Physics their accuracy allows useful applications that can be made based on certain theories. 

Physical constants are a set of fundamental quantities that appear in the basic theoretical equations of physics.

For example, a universal constant of nature is the speed of light in a vacuum (c). The speed of light can be studied in both electromagnetic theory and in relativity theory; in relativity theory, it relies on energy to Mass whose equation can be written as E =mc2. The value of the speed of light never changes and it does not depend on any experimental conditions like the speed of a sound wave changes in some cases therefore, the speed of light is a universal constant

Table Representing Some Important Physical Constants

Quantity

Symbol

Value

constant of gravitation

G

6.67384 × 10−11 cubic meter per second squared per kilogram

speed of light (in a vacuum)

c

2.99792458 × 108 meters per second

Planck’s constant 

h

6.626070040 × 10−34 joule second

Boltzmann constant

k

1.38064852 × 10−23 joule per kelvin

Faraday constant

F

9.648533289 × 104 coulombs per mole

electron rest mass

me

9.10938356 × 10−31 kilogram

proton rest mass

mp

1.672621898 × 10−27 kilogram

neutron rest mass

mn

1.674927471 × 10−27 kilogram

charge on electron

e

1.6021766208 × 10−19 coulomb

Rydberg constant

R∞

1.0973731568508 × 107 per metre

Stefan-Boltzmann constant

σ 

5.670367 × 10−8 watt per square meter per kelvin

fine-structure constant

α

7.2973525664 × 10−3

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