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Instead of broadening up the scope of answer , I would like to divide this question into two parts without any introduction .

1) Do all the time varying EM fields have the ability to transfer energy ?

2) Let us consider a charged particle moving with uniform velocity . It can create time varying EM fields too . Now let us consider an accelerating charged particle , it creates time varying EM fields too and transmits energy . What are the basic points of difference between the ways in which energy is transferred in these two cases ??

Agnivesh Singh
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The website asks to avoid long discussions on the comment section, so I'll post my thoughts here.

1) Time varying EM fields radiate.

2) A particle moving with uniform velocity doesn't radiate. It needs to be accelerated. Take a look at Liénard-Wiechert potencials.

If you have a system where one charged particle is standing still and another one is orbiting it, the one in the center wont radiate, and the orbiting one will. It'll lose energy as it radiates and fall towards the center of the orbit. This was once a paradox in Old Quantum Theory.

Community
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QuantumBrick
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What you're looking for is the Poynting vector, which represents energy flux. It is defined as $$ \mathbf S = \mathbf E \times \mathbf H $$ Time variation in EM fields is not enough to transfer energy; you need perpendicular electric and magnetic fields.

For a derivation of this, I recommend the Wikipedia article on Poynting's theorem.

morrna
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