Machine-translated by Google. Questions are authored in English.
Top

Discussion

The energy per unit time, per unit area transported by the electromagnetic fields is expressed as

  • A.\(\vec{S} = \dfrac{1}{\mu_{o}}(\vec{E} \times \vec{B})\)
  • B.\(\vec{S} = (\vec{E} \times \vec{B})\)
  • C.\(\vec{S} = \mu_{o}(\vec{E} \times \vec{B})\)
  • D.\(\vec{S} = \dfrac{1}{\epsilon_{o}}(\vec{E} \times \vec{B})\)

Answer: A

The energy per unit time per unit area carried by an electromagnetic field is the Poynting vector, \( \vec{S} = \dfrac{1}{\mu_{o}}(\vec{E} \times \vec{B}) \), in watts per square metre, so option A is correct. It points in the direction of propagation. Option B lacks the factor \( 1/\mu_{o} \) and so is dimensionally wrong, option C multiplies by \( \mu_{o} \) instead of dividing, and option D divides by \( \epsilon_{o} \) where the permeability belongs, which would not give a power flux.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.

Subject Categories

Examination Categories

About Us

ExamsRepo

Copyright © 2026 ExamsRepo . All Rights Reserved . With