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Hey, good job you made it through the section about electromagnetic waves, or you could also say this



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lecture about light.



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So let's revisit what we did in this whole section.



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So we started from a special case of the Maxwell's equations.



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This is where we consider the vacuum, which means we set the charge density and the current density



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to zero.



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They are there after we have derived the wave equations or the wave equations for the electric field



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and the magnetic fields, and we did this by using these four modified Maxwell's equations where we



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took two of them, set them into each other, and then the result was a wave equation for E and then



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wave equation for B, and both of these equations are second order in time and second order in space.



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So the solution was an exponential function with time argument and space argument, and the argument



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was a complex number.



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So this means the real part is always something like a cosine.



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So it's really a wave.



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And then we have discussed these waves in detail.



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We have derived the dispersion relation.



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So there's the relation of the frequency and the wave vector.



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So Omega took.



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And then we have also discussed that the way affected the electric field and the magnetic field are



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always perpendicular to each other.



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And then in the last lecture, I think this was quite fun, because there we have discussed the different



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polarizations of light.



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So he had really depends how the real part and the imaginary part of the amplitude of our wave are oriented



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so that we can get linear polarization, circular polarization and also elliptical polarization.



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Now, let's go ahead and talk about another special case.



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This is electromagnetics.