Question

The correct expression for the Poynting vector is __________

(a) S = E X B

(b) S = E X B/2

(c) S = E X B/μo

(d) S = E X B/2μo

This question was posed to me by my college director while I was bunking the class.

Origin of the question is Poynting Theorem topic in division Electrodynamics of Engineering Physics II

Answer 1

The correct option is (c) S = E X B/μo

Easiest explanation: Poynting vector can be defined as the rate at which the energy is carried out of the volume across the bounding surface. It is always in the direction of the propagation of wave, as it is perpendicular to both electric and magnetic field.