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In the Wikipedia article about electromagnetic radiation one can find the following picture: Electromagnetic relationship

But shouldn't the E and B field be 90$^\circ$ out of phase? In the depicted way the energy isn't conserved. At 0 the energy is 0 and at $\frac{\pi}{2}$ the energy is maximal in both fields.

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  • $\begingroup$ I've found the answer here: physics.stackexchange.com/q/4071 $\endgroup$
    – Stein
    Commented May 31, 2014 at 12:41
  • $\begingroup$ If you found the answer on another question, please deleted this one. $\endgroup$
    – JamalS
    Commented May 31, 2014 at 12:45
  • $\begingroup$ @JamalS not necessary, he will lose the points. The moderators can mark it as duplicate if you flag them $\endgroup$
    – anna v
    Commented May 31, 2014 at 13:03

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You are correct about the energy density going to zero, but is this a problem? Remember that this is a traveling wave. The energy in the crests is being carried along ... it doesn't disappear. Energy is conserved. It's moving along.

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