Question

Which of the following Maxwell equation is correct for a non-conducting and lossless medium?

(a) ∇.D=ρv

(b) ∇.D=0

(c) ∇×D=ρv

(d) ∇×E=0

The question was posed to me during an online exam.

My doubt stems from Radiation topic in division Radiation, Baluns & Polarization of Antennas

Answer 1

Correct answer is (b) ∇.D=0

Explanation: Since it is given non-conducting medium, the charge density ρv=0 and current density J=0. The Maxwell equations are:

Faradays Law                : ∇×E=\(-\frac{\partial B}{\partial t}\)

Amperes Law                : ∇×H=\(\frac{\partial D}{\partial t}\)

Gauss Law for electric field     : ∇.D=0

Gauss law for magnetic field  : ∇.B=0