APPENDIX A.
NATURAL
UNITS
The dimensionless constant
11.,
which was named the fine structu re con
stant, has a significance which goes beyond its role in Equation 4.13.
Its
magnitude may be regarded as a measur e of th e strength of the coupling of
particles of charge
±e
to electromagnetic fields.
Indeed, one may call
e
2
the
"strength"
of the interaction
between
±e
and electro
magnetic fields, but it is more "natural" to use th e dimensionless quantity
11.
=
e
2
Jfic
for this purpose.
Since oc is independent of mass it can be used to
describe the electromagneti c interactions of all particles of charge
±e.
An appropriate set of natural units for describing atomic phenomena is
as follows :
In terms of th e natural units and the coupling constant
11.,
the relationships
that were previously found for the hydrogen atom may be expressed as follows:
CHAPTER 4
Variable
mass
length
time
energy
velocity
angular momentum
First Bohr orbit :
APPENDIX A
Natural Unit
Description
m
o
electron rest mass
Ii
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This note was uploaded on 08/06/2008 for the course PHYS 25 taught by Professor Nelson during the Spring '08 term at UCSB.
 Spring '08
 Nelson
 Magnetism

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