Question

In which of the following Integral form of Maxwell equations, the surface is closed?

(a) Amperes law

(b) Gauss Law

(c) Faradays Law

(d) Both Amperes and Faraday law

I have been asked this question in a national level competition.

Asked question is from Radiation topic in portion Radiation, Baluns & Polarization of Antennas

Answer 1

Correct choice is (b) Gauss Law

The best I can explain: The surface integral is closed for the Gauss laws of magnetic and electric fields. It is open for the amperes and Faradays law.

Maxwell Equations:

 Gauss law electric field  : \(\oint_sD.ds =\int_v\rho_v dv \)

 Gauss law magnetic field : \(\oint_sB.ds =0\)

 Faradays law   : \(\int_cE.dl =-\int_s\frac{\partial B}{\partial t}.dS\)

 Amperes law   : \(\int_cH.dl =\int_s(\frac{\partial D}{\partial t} + J).dS\)