Cgs units in electromagnetism pdf

I have attempted to put together a concise set of notes that describes the basics of electromagnetic theory to an audience of undergraduate mathematicians. Cgs electromagnetic units emu, to be used for describing magnetic quantities. However, you may use the table above to do the opposite. In cgs esu, the coulombs law is adopted to connect the mechanical world and. In electromagnetism, a subdiscipline of physics, the magnetic flux through a surface is the surface integral of the normal component of the magnetic field b passing through that surface. For problems in mechanics, the difference is trivial, amounting only to some powers of ten. One might look at the page on lorentzheaviside units on the wikipedia. All cgs mechanical units are unambiguously derived from these three base units. Gaussian units constitute a metric system of physical units. At the atomic scale, electromagnetism admittedly in conjunction with some basic quantum e ects governs the interactions between atoms and molecules. It is also called the gaussian unit system, gaussian cgs units, or often just cgs units. The science of electromagnetic phenomena is defined in terms of the electromagnetic force, sometimes called the lorentz force, which includes both electricity and magnetism as elements of one. Birge, on electric and magnetic units and dimensions, american journal of physics, may 1934 pp.

Purcells classic textbook has introduced students to the world of electricity and magnetism. Therefore, we will explain both unit systems and look at how to convert successfully between them. Mks unit cgs unit conversion mass kilogram gram 1kg 103gm distance meter centimeter 1m 102cm energy joule erg 1j 107erg force newton dyne 1n 105dyne. Electromagnetic units two divergent systems of units established themselves over the course of the 20th century. Up to this point, however, most students have used. The centimetergramsecond system of electromagnetic units emu has been used in magnetism since the latter part of the 19th century. Electromagnetism and relativity physics and engineering. For example, in mks units it may be represented in terms of the quantum of electric charge e, the quantum of magnetic flux fluxoid.

So the answer is that the speed of light appears only because of complicated ways of changing the units. Maxwells equations in cgs units are the lorentz force is in fact, an even better definition rationalized heavisidelorentz units of the charges and fields can be made as shown in the introduction to field theory in chapter 32. Gaussian units and cgs emu are the same for magnetic properties. The centimetregramsecond system of units abbreviated cgs or cgs is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. This is a working set of lecture notes for the part a electromagnetism course, which is part of the mathematics syllabus at the university of oxford. The maxwell was recommended as a cgs unit at the international electrical congress held in 1900 at paris. The choice for the units of the fields well in fact for the units of electric charge and magnetic poles is discussed at length in this rather old but still relevant. An alternative view of the fine structure constant and its. What is the value of permittivity of free space in cgs units.

The word electromagnetism is a compound form of two greek terms, elektron, amber, and magnetis lithos, which means magnesian stone, a type of iron ore. In this chapter, the cgs esu electrostatic unit unit system is used so that electromagnetic elds e statvoltcm 300 voltcm 3 104 voltm and b gauss 10 4 t have the same dimensions. A modification of the gaussian system of units the physics and technology system. Physics notes for class 12 chapter 6 electromagnetic i. This eld is constant between the plates along the zaxis. Contents v multiple systems v the laws of ampere and coulomb v the approach taken by the cgs system v the e. Converting mass, distance, and mechanical units only involves powers of 10. A second, at one time defined as a fraction 186400 of a day, is now defined as 9 192 631 770 times the period of a hyperfine line emitted in the spectrum of the 3 cs caesium atom. Gausss law for magnetism states that there are no magnetic charges also called magnetic monopoles, analogous to electric charges. It is the force that underlies the periodic table of elements, giving rise to all of chemistry and, through this, much of biology. The cgs system has been largely supplanted by the mks system, based on metre, kilogram, and second. The magnetic force equation itself takes a slightly di. A units in magnetism 187 magnetic quantities and units.

It requires introducing a few other factors of c into common electromagnetic formulas. Electric and magnetic units the esu and emu unit systems are cgs systems. Electromagnetic units rensselaer polytechnic institute. The term cgs units is ambiguous and therefore to be avoided if possible. The abbreviations are mmetre, ggramme, nnewton,jjoule,ttesla,ggauss,aamp,oeoersted,wbweber,mxmaxwell. Oct 05, 2015 dear friends, as you know, in cgs units we have vacuum permeability as unity 1. But the dyne, erg, or poise, have no fundamental signi. In other versions of the cgs system it can be different. Conclusion glossary bibliography biographical sketches summary the paper presents a description of the importance of a system of physical quantities and units and the niche that it occupies in everyday. Qualifying examination, part 2 solutions problem 1. One is called the cgs, which stands for centimetergramsecond, denoting the root measures upon which. This system is the most common of the several electromagnetic unit systems based on cgs centimetregramsecond units.

A guide to the different approaches used to define measurement units in the physics of magnetism and electrostatics. Beck, spacecharge waves and slow electromagnetic waves. The electromagnetic force is carried by electromagnetic fields composed of electric fields and magnetic fields, is responsible for electromagnetic radiation such as light, and is one of the four fundamental interactions. It is also called the gaussian unit system, gaussiancgs units, or often just cgs units. The cgs unit of energy is a erg, equal to one gm cm2 sec. I direct current dc if the burden of two systems of measurement for common quantities english vs. Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Physics and tec hnology system of units for electrodynamics. The cgs unit of viscosity is a poise, equal to one gm cm. Second edition dover books on physics on free shipping on qualified orders. Classical and relativistic approaches, is an extended form of the previous two editions of the books titled electromagnetics.

The gaussian unit system is just one of several electromagnetic unit systems within cgs. There are cgs electrostatic units esu, to be used in electrostatics. Mechanical and other kinds of engineers and engineering students who need knowledge on electromagnetism will find the book invaluable. Here is a sampling of equations of electrodynamics written in cgs units4 f 12 e1e2 r2 12 r. Magnetic units of measurement chapter 14 magnetism and electromagnetism pdf version.

Due to an early lack of standardization in the science of magnetism, we have been plagued with no less than three complete systems of measurement for magnetic quantities. Formulas for physical laws of electromagnetism such as maxwells equations need to be adjusted depending on what system of units one uses. Gravity and electromagnetism are radiant force fields. This text advances from the basic laws of electricity and magnetism to classical electromagnetism in a quantum world. Its a bit instructive to look at the energy densities of the fields. This practical unit was previously called a line, reflecting faradays conception of the magnetic field as curved lines of magnetic force, which he designated as line of magnetic induction. This combined force law is known as the lorentz force. This phenomenon is called electromagnetic induction. It has seven base units and two supplementary units. It features hundreds of new examples, problems, and. The two systems differ only in the scale of two out of the three base units centimetre versus metre and gram versus kilogram, respectively, while the third unit second as the unit of time is the same in both systems. Suitable for firstyear graduate students in physics who have taken an undergraduate course in electromagnetism, it focuses on core concepts and related aspects of math and physics.

There is no such thing as the cgs unit for any electromagnetic quantity. There are at least four ways that the cmgs concept has been extended into the world of electromagnetism. Why was the cgs system used in physics, particularly. The new book, at the difference of the previous ones, contains four new appendices. Contrast this with mechanics, where f ma regardless of whether we measure length in units of meters, inches, furlongs, or lightyears. An intermediate level course richard fitzpatrick professor of physics the university of texas at austin. Conversion between these base units and all the derived units are quite simply given by an appropriate power of 10. Classical electrodynamics, third edition, by john david jackson, john wiley and sons, 1998.

Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles. Conversion of the mksa units to the mks and cgs units science. Derivation of cgs units in electromagnetism cgs approach to electromagnetic units. All cgs mechanical units are unambiguously derived from these three base units, but there are several different ways of extending the cgs system to cover electromagnetism. Electromagnetic units, the giorgi system, and the revised.

The term cgs units is ambiguous and therefore to be avoided if. The science of electromagnetic phenomena is defined in terms of the electromagnetic force, sometimes called the lorentz force, which includes both. Introduction within the metric system, there are actually two separate selfconsistent systems. Dec, 2015 the physics and technology system of units pt. Physics and technology system of units for electrodynamics. Physics notes for class 12 chapter 6 electromagnetic i nduction whenever the magnetic flux linked with an electric circuit changes, an emf is induced in the circuit. These equations have needless extra constants not of nature in them so we dont like to work in these units. Pdf physics and technology system of units for electrodynamics. Deceptively clear and comprehensive chapters, then one got stuck in the math to do the problems. Unit systems in electromagnetism university of surrey. Review of the classical equations of electricity and.

The numeric value for the vacuum permeability is 0. If the burden of two systems of measurement for common quantities english vs. An introductory course, third edition covers the principles of electromagnetism. Magnetic flux is defined as the number of magnetic field. The unit name honours james clerk maxwell, who presented a unified theory of electromagnetism. Sep 18, 2014 cgs is coherent, and suitable for setting c1. All cgs mechanical units are unambiguously derived from these three base units, but there are several different ways in which the cgs system was extended to cover electromagnetism. Conversion of the mksa units to the mks and cgs units. The course will use cgs units, as does our textbook classical electrodynamics, 2nd ed.