- #1
crick
- 43
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Maxwell equation in absence of charges and currents are
$$\nabla \cdot \bf{E} = 0 \\ \nabla\cdot B=0 \\ \nabla \times E=-\frac{\partial B}{\partial t} \\\nabla \times B=\mu \epsilon \frac{\partial E}{\partial t}$$
Wave equation is $$\nabla ^2 \bf{E}=\mu \epsilon \frac{\partial^2 E}{\partial t^2}\tag{1}$$
How can I prove that, given a solution ##\bf{E}## that satisfies both Maxwell equations and ##(1)##, then the vector ##\bf{E+E'}## where ##\bf{}{}E'## is a vector such that ##\nabla \times \bf{}{}E'=0## (and ##\nabla \cdot E \bf{}##) is a solution of ##(1)##?
As I found explained here https://www.photonics.ethz.ch/fileadmin/user_upload/Courses/EM_FieldsAndWaves/WaveEquation.pdf,
Can anyone provide a proof of the fact that a non divergence free (but irrotational) vector can be solution of wave equation without being solution of maxwell equation?
$$\nabla \cdot \bf{E} = 0 \\ \nabla\cdot B=0 \\ \nabla \times E=-\frac{\partial B}{\partial t} \\\nabla \times B=\mu \epsilon \frac{\partial E}{\partial t}$$
Wave equation is $$\nabla ^2 \bf{E}=\mu \epsilon \frac{\partial^2 E}{\partial t^2}\tag{1}$$
How can I prove that, given a solution ##\bf{E}## that satisfies both Maxwell equations and ##(1)##, then the vector ##\bf{E+E'}## where ##\bf{}{}E'## is a vector such that ##\nabla \times \bf{}{}E'=0## (and ##\nabla \cdot E \bf{}##) is a solution of ##(1)##?
As I found explained here https://www.photonics.ethz.ch/fileadmin/user_upload/Courses/EM_FieldsAndWaves/WaveEquation.pdf,
Although the field $E(r, t)$ fulfills the wave equation it is not yet a rigorous solution of Maxwell’s equations. We still have to require that the fields are divergence free, i.e. $∇·E(r, t) = 0$. This condition restricts the k-vector to directions perpendicular to the electric field vector $(k·E_0 = 0)$.
Can anyone provide a proof of the fact that a non divergence free (but irrotational) vector can be solution of wave equation without being solution of maxwell equation?