In advanced physics, the fine structure constant is synonymous with Sommerfeld’s constant. It is denoted by the Greek letter 𝜶 (alpha). It is a dimensionless physical constant. Fine-Structure Constant characterises the strength of electromagnetic interactions between any two elementary charged particles.
|
Table of Contents: |
Measurement
Being a dimensionless quantity, Fine-Structure Constant has the same numerical value in all system of units. Which is approximately
Definition
Fine-Structure Constant characterises the strength or magnitude of coupling of any elementary charged particle(e) with the given electromagnetic field. Mathematically 𝜶 can be expressed in terms of other fundamental physical constants as follows-
Where,
- \(\begin{array}{l}\bar{h} = \frac{h}{2\Pi }\end{array} \)is the reduced Planck’s Constant
- e is the elementary charge (e=1.602176634 × 10-19C)
- c is the velocity of light in vacuum (c=299792458 m/s)
- ε0 is the permittivity of free space.
- µ0 is the Permeability of free space.
- Ke is the Coulomb constant.
- RK is the von Klitzing constant.
- Z0 is the impedance of free space.
In non-SI units
The value of this dimensionless physical quantity can be expressed in many units.
Electrostatic CGS unit
In electrostatic CGS units, electric charge is measured using statcoulomb and is defined assuming permittivity factor 4πε0 or Coulomb constant ke is 1 and is dimensionless. Thus, the value of fine structure constant turns out to be-
Natural unit
High energy physics commonly use natural units, where ε0 = c = ħ = 1. here, ε0 is the permittivity of free space. Thus the value of fine structure constant turns out to be-
Atomic units
According to atomic units,
Physical interpretations
The physical interpretation of Fine Structure Constant is plenty. Some are listed below-
- In quantum electrodynamics, Fine Structure Constant 𝜶 is directly related to coupling constant.
- In solid state physics and electrical engineering, 𝜶 is one-fourth product of the characteristic impedance of free space.
- Within the Bohr model, 𝜶 gives the maximum positive charge of an atomic nucleus that will allow a stable-orbit around it.
- 𝜶 gives the probability of emission or absorption of an electron by a photon.
- It also has got wide applications in low energy physics, particularly in electroweak theory. Also, some properties of subatomic particles exhibit a strong correlation with 𝜶.
Hope you have understood about fine structure constant(𝜶). Including, definition, formula, terms along with units, values in non-SI units and physical interpretation of alpha.
Physics Related Topics:
| Mu Naught Value |
| Band Theory Of Solids |
| Value Of Planck’s Constant |
| Permittivity And Permeability |
Stay tuned with BYJU’S for more such interesting articles. Also, register to “BYJU’S-The Learning App” for loads of interactive, engaging physics-related videos and unlimited academic assistance.
Frequently Asked Questions – FAQs
What is permittivity of free space?
ε0 = 8.854187817 × 10-12. F.m-1 (In SI Unit)
What is electromagnetic force ?
State Faraday’s first law of electromagnetic induction.
Define fine-structure constant.
What is electromagnetism ?
Define Fine Structure Constant
Its numerical value is:
What is the value of Fine Structure Constant in Atomic Unit?
Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin!
Select the correct answer and click on the “Finish” button
Check your score and answers at the end of the quiz
Visit BYJU’S for all Physics related queries and study materials
Your result is as below
Comments