Question

The continuity equation is a combination of which of the two laws?

(a) Ohm’s law and Gauss law

(b) Ampere law and Gauss law

(c) Ohm’s law and Ampere law

(d) Maxwell law and Ampere law

The question was asked during an online exam.

My question is taken from Continuity Equation in section Electric Fields in Material Space of Electromagnetic Theory

Answer 1

Correct option is (b) Ampere law and Gauss law

The explanation is: I = ∫ J.ds is the integral form of Ohm’s law and Div (J) = dq/dt is the Gauss law analogous to D. Through these two equations, we get Div(J) = -dρ/dt. This is the continuity equation.