Question

Which of the following option gives correct equation for Gauss' Law of magnetism?
1. \(\oint \overrightarrow{E}.\overrightarrow{dA}= {q\over {\epsilon_0}}\)
2. \(\oint \overrightarrow{E}.\overrightarrow{dA}= 0\)
3. \(\oint \overrightarrow{B}.\overrightarrow{dA}=0\)
4. None of the above

Answer 1

Correct Answer - Option 3 : \(\oint \overrightarrow{B}.\overrightarrow{dA}=0\)

CONCEPT:

• Gauss's law for magnetism is one of the four of Maxwell's equations.
• It states that the magnetic field B has divergence equal to zero.

The integral form of Gauss's law for magnetism states:

\(\oint \overrightarrow{B}.\overrightarrow{dA}=0\)

where B is the magnetic field and dA is any closed surface vector whose magnitude is the area of an infinitesimal piece of the surface, and whose direction is the outward-pointing surface normal.

• Gauss's law for magnetism states that magnetic flux through a closed surface is always zero.

EXPLANATION:

Magnetic flux through a closed surface is given by: 

\(\phi = \oint \overrightarrow{B}.\overrightarrow{dA}\)

and Gauss's law for magnetism states that magnetic flux through a closed surface is always zero.

\(\oint \overrightarrow{B}.\overrightarrow{dA}=0\)

So the correct answer is option 3.