From: ellocomateo@free.fr
2012-05-10 01:32, Salmon Egg scripsit:
> In article<4faac343$0$20196$426a34cc@news.free.fr>,
> "Mat' G." wrote:
>
>> Hello,
>>
>> I cannot visualize the following, can someone please help me?
>>
>> Given a cartesian coordinate system {x,y,z} and a plane wave of light
>> propagating in the z direction and polarized along x, which of the
>> following is non zero?:
>>
>> \partial E_x /\partial x
>> \partial E_x /\partial y
>> \partial E_x /\partial z
>>
>> I would say only the first and last one because the electric field
>> oscillates/varies along x, and propagates/varies along z.
>>
>> Am I wrong? Thank you for commenting.
>
> I presume you are talking about a UNIFORM PLANE WAVE. It is traveling in
> the z direction and there is only an E component in the x direction.
> That is Ey is zero and Ez is zero. Thus only the last derivative is
> nonzero. That is, If the wave is the real part of Ez = Eo exp j(wt - z),
>
> Ex/z = the real part of -j [Eo exp j(wt - z)].
>
> That is the case for a single frequency, but a more complicated wave is
> just a superposition such terms.
>
Alright thank you and Timo for your replies.
Now, it is clearer now.
I'll now post a similar question in the newsgroup regarding a
quadrupole. I also cannot visualize this.
Best regards,
Mat
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