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A plane electromagnetic wave travels in vacuum along z - direction. What can you say about the directions of its electric and magnetic field vectors ? If the frequency of the wave is 30 MHz, what is its wavelength ? |
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Answer» Solution :Here `vec(E )` MUST be along + X axis and `vec(B)` must be along + Y axis, so that direction of `vec(E )xx vec(B)=` direction of `hat(i)xx hat(J)=` direction of `hat(k)=` direction of + Z axis = direction of propagation of electromagnetic wave. In both of above cases, `vec(E )` and `vec(B)` will OSCILLATE perpendicular to each other in XY - plane, perpendicular to direction of propagation of electromagnetic wave. Since given electromagnetic wave propagates in vacuum, its speed would be equal to c. Now, according to formula, `c=v lambda` `therefore lambda = (c )/(v)=(3xx10^(8))/(30xx10^(6))=10m` |
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