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A conductor of resistance 0.5 \( \Omega \) carries 10 A. The inward flux of the Poynting vector over its surface is

  • A.50 W
  • B.5 W
  • C.0.5 W
  • D.zero

Answer: A

Correct answer: 50 W

The inward flux of the Poynting vector over the conductor’s surface must equal the power dissipated inside it, which is \[ I^2R = 10^2 \times 0.5 = 50\ \mathrm{W}. \] This is the theorem’s most direct check: the energy dissipated as heat did not travel along the wire but entered radially through its surface from the surrounding field, and the two figures agree exactly.

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