Practice portal › Electromagnetic Waves › Maxwell's Equations and the Production of EM Waves
Asked in GSEB Board March 2018 · Sources: the accelerated charge and Hertz
Idea: close to an oscillating charge the fields are dominated by induction rather than radiation, and the two zones behave quite differently.
In that near zone E and B are a quarter of a cycle apart, a phase difference of π/2, so the product EB averages to zero over a cycle and no energy streams outwards.
Their magnitudes also fall very steeply there, as 1/(r³).
Only farther out do the radiated parts, in phase and falling as 1/r, take over.
So the phase difference is π/2 and the decrease is as r⁻³.
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