In a $$DC$$ machine, which of the following statements is true?

Which of the following statements holds for the divergence of electric and magnetic flux densities?

Consider the following statements with reference to the equation $$\nabla.\overrightarrow J=-\frac{\partial\rho}{\partial t}$$

1. This is a point from the continuity equation
2. Divergence of current density is equal to the decrease of charge per unit volume per unit time at every point.
3. This is Maxwell's divergence equation
4. This represents the conservation of charge.

Select the correct answer.

The concept of an electrically short, medium, and long line is primarily based on the