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The Poynting vector in a region containing only a static electric field is

  • A.equal to the square of the electric field divided by the impedance
  • B.zero, there being no magnetic field to cross it with
  • C.equal to the electric energy density divided by the speed of light
  • D.directed along the electric field lines

Answer: B

Both fields must be present for the cross product to be non-zero, so a purely electrostatic region has no energy flow. Energy is stored there but nothing is transported, which is exactly what one would expect of a static situation.

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