TeXes Science Practice Test

What does Gauss's law of magnetism state about net magnetic flux?

1. It can be positive

2. It can be negative

3. It is always zero

4. It varies in closed regions

The correct answer is: It is always zero

Gauss's law of magnetism states that the net magnetic flux through any closed surface is always zero. This principle arises from the observation that magnetic field lines do not begin or end; they loop infinitely in space, meaning that for every magnetic field line entering a closed surface, there is a corresponding line exiting. Since the total number of lines entering and leaving must balance, the net magnetic flux remains zero. Thus, the correct understanding of this law emphasizes the intrinsic nature of magnetic fields and their lines of force, reinforcing that no magnetic monopoles exist (as we describe electric charges). This conclusion is fundamental to electromagnetic theory and helps explain various physical phenomena involving magnetic fields.