InterviewSolution
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InterviewSolution
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A standing electromagnetic wave with electric component E=E_(m) cos kx. Cosomegat is sustained along the x axis in vacuum. Find the magnetic component of the wave B(x,t). Draw the approximate distribution pattern of the wave's electric and magnetic components (E and B) at the moments t=0 and t=T//4, where Tis the oscillation period. |
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Answer» Solution :Here `oversetrarr(E) = oversetrarr(E_(m)) cos kx cos omegat` From div `oversetrarr(E) = 0` we get `E_(mx) = 0` so `oversetrarr(E_(m))` is in the `y - z` PLANE. Also `(del oversetrarr(B))/(del t) =- oversetrarr(DELTA) xx oversetrarr(E) =- Delta cos kx xx oversetrarr(E_(m)) cos omega t` `= oversetrarr(K) xx oversetrarr(E_(m)) sin kx cos omegat` so `oversetrarr(B) = (oversetrarr(k)xxoversetrarr(E_(m))/(omega)) sin kx sin omegat = oversetrarr(E_(m) sin kx sin omegat` Where `|oversetrarr(B_(m))| = (E_(m))/(C)` and`oversetrarr(B_(m)) _|_ oversetrarr(E_(m))` in the `y - z` plane. At `t = 0, oversetrarr(B) = 0, E = E_(m) cos kx` At `t = T//4 oversetrarr(E) = 0, B = B_(m) sin kx` |
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