Question

. At one instant, the electric and magnetic fields at one point of an electromagnetic wave are ! = 300! + 50! ? 200! V/m, and ! = !! 1.7! ? 3.9! + !!

Answer 1

Something seems wrong with your question.

Anyways, assuming that you know the constants, the poynting vector can be easily calculated by

$\mathbf{S} = \mathbf{E} \times \mathbf{H}$

where

• E is the electric field;
• H is the magnetic field.

Interpretation:

at

where J_f is the current density of free charges and u is the electromagnetic energy density

$u = \frac{1}{2}\! \left(\mathbf{E} \cdot \mathbf{D} + \mathbf{B} \cdot \mathbf{H}\right)\! ,$

where

• E is the electric field;
• D is the electric displacement field;
• B is the magnetic flux density;
• H is the magnetic field.

Good luck....