# What is the Close Surface in Electromagnetics?

Close Surface is a fundamental term. It is necessary to understand it thoroughly for studying many terms in Electromagnetics. This article defines the closed surface and its significance.

## What is an open surface or normal surface?

We know that any surface is characterized by its area. We can say the surface, open surface or normal surface if it posses the only area. Consider, for example, the circle and the square shown in the figure below. They are planer diagrams and bear only surface area. Such surfaces are normal surfaces or open surfaces.

## What is the difference between close surface and open surface?

The close surface is the outer surface of some actual object. Let us consider the cube below. Now we know that the actual 3D object will have the volume and outer surface area.

So the basic difference between the normal (open) surface and the

Actually by saying ‘a

## The significance of Close Surface in Electromagnetics

#### Gauss’s Law in Electrostatic is defined for the closed surface

It states that the total electric flux coming out of any closed surface is equal to charge enclosed within it.

#### Close surface is also important in Magnetic Gauss’s Law

Similar to Electrostatics, the Gauss law is also defined in Magneto-statics. It states as total magnetic flux coming out of any closed surface is always zero.

#### Closed surface forms the basis for definition of the Divergence

The divergence of the vector field at the given point is defined as the net outward flux per unit infinitesimal volume formed at that point. The infinitesimal volume at the point is nothing but a closed surface.

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Tag:Electromagnetism