# What is the Close Line in Electromagnetics?

Close Line or Close Path is one of the fundamental terms of an Engineering study. Its proper intuition is necessary to understand many terms in the Electromagnetics. This article defines the close line and its significance.

## What is a normal line or an open line?

When we say a line then as everybody knows, we mean to say the length. So a line is characterized by the length. The geometric one-dimensional shape having a length can be broadly called as a line. All of us have drawn the lines in our student life which may look like a figure below.

## What is the difference between the normal line and the close line?

In simple words, the close path is a loop having no end. When we draw any normal line of any random length then we must start it from a certain point and end it on another point. In other words, a line has two endpoints.

But if we draw the line in such a way that the starting and ending point is exactly the same then it would form a loop. And such a loop is also called as a closed line.

The normal line can only have the length. But a closed line or loop possesses the length as well as the area enclosed within the loop. Consider for example the simple close line, the circle. We know that the length of a circle is given by circumference as well as we can find its area. Isn’t it?

So from Electromagnetics perspective, a normal line is having only the length but a close line is the one which is having both the length and the enclosed area.

## The significance of Close Path in Electromagnetics

#### Ampere’s Law is defined for the close line

It states that the close line integration of magnetic intensity (H) is equal to the current enclosed by that loop (close line).

#### It forms the basis for the definition of curl of a vector

A curl of a vector field is defined as a maximum circulation of the given field per unit area (tending to zero) bounded by the closed path.

*Suggested Read: What is the close surface?Suggested Community: Electromagnetics for GATE & ESE*

Tag:Electromagnetism