budynek aiut AIUT sp. z o. o.
★  HenrykDot.com   ★
is the online companion to a series of books published by AIUT under the common main title
"Physics of My Imaginary Space-Time" by Henryk Dot.
POLSKI

last update
20/01/2023
Home

Physics 3 - Maxwell
Note from the Author
Table of Contents
What is this book
Historical facts
New aspects
Fully erroneous
Incorrectly interpreted

Physics 3 - Chapter 1
Equations
Complex vectors form
The Most General form
The General Solution

Physics 3 - Chapter 2
Solutions
Initial conditions
Non-homogeneous equation
Solution for three-directions
The four laws

Physics 3 - Supplement
Fermat's proof
Beal's conjecture
Pythagorean triples
Inertial mass
Gravity constans big G
What does the Moon look at?

Physics 3 - Final notes
Final notes

Physics 4 - New book
Entry

Contact email: henryk.dot(at)aiut.com
"Subject" should begin with
a digit corresponding to the day
of the week., e.g. Sunday=7




Books published by AIUT
are found in libraries according to the list of compulsory copies.

Second Edition of "Fizyka 3"
ISBN 978-83-926856-1-6
Fizyka
can be bought in Warsaw
in the Academic Bookstore
PW Publishing House
Noakowskiego street 18/20

and in Katowice
in the bookstore "Liber"
Bankowa street 11.
(area of Silesian University)

English edition of "Physics"
ISBN 978-83-926856-2-3
Fizyka
is also in libraries
and the distribution method should be asked wydawca@aiut.com.


2.2.3.  Solution for nonhomogeneous equation

     Nonhomogeneous one-direction equivalent of equation (2.3) is expressed as:

2w32 (2.32)
     Textbooks ([L2]–Marcinkowska, [L3]–Krzyzanski) contain solution of this equation. Applying notations used in this book, it is written as:
F(x, τ) = g1(x, τ) + g2(x, τ) , (2.33)
where g1(x, τ) and g2(x, τ) represent solutions derived from initial conditions (2.16-2.28) and related forcing
2w34 (2.34)
2w35 (2.35)
     This is correct solution; however, it cannot be applied for solving Maxwell’s equations. This is due to assumed conditions (used in above textbooks) which were required to prove correctness of the solution, but at the same time imposing significant limitations affecting its application.
The deciding factor determining its unsuitability comes from the assumption that forcing
 f (x, τ)  begins at time  τ = 0   and then only from this point the solution is determined.
     Such assumptions are justified when performing analysis of already mentioned above string equation, but for Maxwell’s equations we should search for a solution with leading forcing function without limitations for analyzed time point.
      Textbook [L2] by Marcinkowska applies additional requirement for limited and enclosed space   (x, τ) , which further limits application of this solution.
     It should be noted that for Maxwell’s equations, solution derived from initial conditions in some considerations may become irrelevant. This is because initial conditions in Maxwell’s equations represent a wave created by forcing function from another position in space, thus being a component of a solution itself.
      Due to limitations mentioned above, it was necessary to derive restriction-free solution. Presented solution is easy to understand since it is based on elementary knowledge regarding differential equations without need of additional knowledge about other theorems.
After substitution of variables in equation (2.32) we obtain
2w34 (2.36)
and we arrive at final formal solution
2w34 (2.37)
     However, deriving practical equations from this is not simple, so we will follow an easier way.
The drawing below (Fig.2) clarifies meaning of individual variables and operations performed.
x τ Sorry, your browser does not support inline SVG.
x = x0
τ = τ0
τ = τC
O(u0,v0)= O(x0, τ0)
A(uA,v0)
C(x0c)
B(u0,vB)
v
vC
vB
u
uC
uA
Fig.2    
Drawing legend:
     –  u, v, x, τ   denote axis of coordinates,
     –  Fo(uo , vo)  represents value of the function in point (uo , vo), i.e. (xo , τo)
                       marked on drawing as O(xo , τo) = O(uo , vo),
     –  Fo(uc= xo + τc , vc= xo - τc)  represents value in point (xo , τc)
                        marked on drawing as C(xo , τc) , which we can consider as
                       an initial value of function F().
     –  The wave moving in the direction of increasing values of x is denoted by red line
          and respectively blue color represents the wave moving towards decreasing values of x.

    Integral 2w37a represents change of a value of function    F(x, τ)
while traveling from point  C(xo , τc)  to point  O(xo , τo),  .e. change of value of function  F(x, τ)
in point  xo   from time =  τc  to time =  τo  ,  while  τc ≤  τo .

     For traveling from point C to point O (as marked on Fig.2), we will apply the following relation:
2w38 (2.38)

      In further calculations, we will be frequently performing various substitutions of functions and variables.
In order to facilitate reader with easier following of these calculations, basic relations are being repeated below:
      u = x + τ    ,     v = x - τ (2.39)
   2w40a 2w40b (2.40)
      u - v = 2 ⋅ τ    ,     u + v = 2 ⋅ x; (2.41)
      F(x, τ) = Fo(u, v) (2.42)
   2w43 (2.43)
      Fo(x, τ) = Fo(x + τ, x - τ) (2.44a)
      Fo(u, v) = Fo(u, 2 ⋅ x - u) = Fo(2 ⋅ x - v, v) (2.44b)
      Fo(u, v) = Fo(u, u - 2 ⋅ τ) = Fo(v + 2 ⋅ τ, v) (2.44c)

      Consequently; the following relations apply:
2w45 (2.45)
2w46 (2.46)
2w47 (2.47)
2w48 (2.48)
2w49 (2.49)
2w50 (2.50)
2w51 (2.51)
2w52 (2.52)
2w53 (2.53)
2w54 (2.54)
Formula (2.50) can be applied in w (2.38), thus we obtain
2w55 (2.55)
      The right-side components in (2.55) can be easily determined for fixed  τ  and for selected point  xo  on  x  axis, from following relations:
2w56 (2.56)
2w57 (2.57)
and applying (2.54) we have
2w58 (2.58)
2w59 (2.59)
Based on (2.40)
2w60 (2.60)
therefore
2w61 (2.61)
2w62 (2.62)
and consequently
2w63 (2.63)
2w64 (2.64)
     Inserting these values into do (2.55), we finally obtain:
2w65 (2.65)
     This is equivalent of formula (2.35) and it was derived without any limitations for value of time  τc ,
which can be extended even to  -∞.
     Constant  F(xo, τ)  results from integral of function  f(x, τc
for time periods before  τc .
     For deriving formula (2.35), it was assumed that for τ < τc function  f(x, τc) = 0  , thus integral of
this function (our value of  F(xo , τc)  ) also equals zero.
      For solving Maxwell’s equations, there is no need to consider solutions derived from initial conditions
 F(x, τc)  and  ∂F(x, τc) /∂τ  ,  these can be considered for other than Maxwell’s equations while
relating these conditions to sources  f(x, τ) .

      Variable  τo   was introduced to demonstrate equivalency of formulas (2.35) and (2.65).
Since this variable represents actual time, we can present concise and clear formulas (without losing generality), by selecting  τo = 0.


     In this case, formula (2.65) is expressed as follows:
2w66 (2.66)
By extending time τc to negative infinity, we can eliminate the constant  F(xo, τc)  , therefore:
2w67 (2.67)
2w68 (2.68)
      Integration constants (2.61) and (2.62) in formulas (2.63) and (2.64) are identical; they are also present
in formula (2.65) but with opposite signs, so they eliminate each other. The values of  ∂Fo(u, vo) / ∂u   and  ∂Fo(uo , v) / ∂v  as shown on Fig.2 represent values of these derivatives in points where time axis  τ   crosses lines corresponding to variables  uo and  vo .   These variables represent respectively a wave traveling towards decreasing  x values and a wave traveling towards increasing  x values.
      As in homogenous equation, these waves can be separated and named  Fv(u, vo)   and  Fu(uo , v) .

     Therefore
    Fo(uo, vo)  = Fu(uo , vo)  + Fv(uo, vo (2.69)
2w70 (2.70)
2w71 (2.71)
     Integration in respect to  τ , in formula (2.70) is performed along straight line  vo  which means that
  v = x - τ = vo = xo - τo = xo ,  czyli  τ = xo - x   i  dτ = dx .
     In order to distinguish variable  x   derived from substitution of  τ  (based on dτ = dx )  we will denote it with apostrophe  x'   so equation (2.70) can be expressed as:
2w72 (2.72)
Similarly, integration in (2.71) is performed along straight line  uo , which means that
  u = x + τ = uo = xo + τo = xo ,  herefore,  τ = xo - x  and  dτ = - dx  and formula (2.71) takes following form
2w73 (2.73)
The formulas become even more readable when applying additional auxiliary variable  r .
2w74 (2.74)
2w75 (2.75)

      Formulas (2.69), (2.74) and (2.75) represent solutions of general form (2.32)
of one-direction nonhomogeneous Maxwell’s equation.




  © 2020 Henryk Dot -