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An electromagnetic wave emitted by an elementary dipole propagates in vacuum so that in the far fold zone the mean value of the enrgy flow density is equal to S_(0) at the point removes from the dipole by a distance r along the perpendicualr draws to the dipole's axis. Find the mean radiation power of the dipole. |
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Answer» Solution :We know that `S_(0)(r ) prop (1)/(r^(2))` AT other angles `S(r, THETA) prop sin^(2) theta` Thus `S(r, theta) = S_(0) (r )sin^(2) theta = S_(0)sin^(2) theta` Average power radiated `= S_(0) xx 4PI r^(2) xx (2)/(3) = (8pi)/(3) S_(0)r^(2)` (Average of `sin^(2) theta` over whole spher is `(2)/(3))` 
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