DescriptionLine integral of scalar field.gif	English: Line integral of a scalar field, f. The area under the curve C, traced on the surface defined by z = f(x,y), is the value of the integral. See full description. فارسی: انتگرال خطی یک میدان اسکالر f. مقدار انتگرال مساحت زیر منحنی C تعریف شده توسط سطح (z = f(x,y است. Français : L′intégrale curviligne d′un champ scalaire, f. L′aire sous la courbe C, tracée sur la surface définie par z = f(x,y), est la valeur de l'intégrale. Italiano: Integrale di linea di un campo scalare, f. Il valore dell'integrale è pari all'area sotto la curva C, tracciata sulla superficie definita da z = f(x,y). Русский: Иллюстрация криволинейного интеграла первого рода на скалярном поле.
Date	24 July 2012
Source	Own work
Author	Lucas Vieira
Permission (Reusing this file)	Public domainPublic domainfalsefalse I, the copyright holder of this work, release this work into the public domain. This applies worldwide. In some countries this may not be legally possible; if so: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.
Other versions	Video version, higher resolution, longer pauses Line integral of a vector field Static version of this abstract scalar field, with scale

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This image was selected as picture of the day on Wikimedia Commons for 11 April 2013. It was captioned as follows: English: Line integral of a scalar field, f. The area under the curve C, traced on the surface defined by z = f(x,y), is the value of the integral. Other languages: Deutsch: Illustration eines Kurvenintegrals erster Art über ein Skalarfeld, f. Das Gebiet unter der Kurve C, abgetragen auf die Oberfläche definiert von z = f(x,y), ist der Wert des Integrals. English: Line integral of a scalar field, f. The area under the curve C, traced on the surface defined by z = f(x,y), is the value of the integral. Français : L′intégrale curviligne d′un champ scalaire, f. L′aire sous la courbe C, tracée sur la surface définie par z = f(x,y), est la valeur de l'intégrale. Italiano: Integrale di linea di un campo scalare, f. Il valore dell'integrale è pari all'area sotto la curva C, tracciata sulla superficie definita da z = f(x,y). Magyar: Az f skalártér vonal menti integrálja. Az integrál értéke a z=f(x,y) függvénnyel definiált C görbe alatti terület. Nederlands: Lijnintegraal van een scalair veld, f. Het gebied onder de curve C, getraceerd op het vlak gedefinieerd door z = f(x,y), is de waarde van de integraal. 한국어: 선적분의 스칼라장, f. 적분의 값은 z = f(x,y)에 의해 표면에 정의된 값을 따라서 그린 곡선 C 아래의 면적이다. 中文： 标量场的曲线积分，曲线C下面的区域表面积分值定义为z = f(x,y)。

A scalar field has a value associated to each point in space. Examples of scalar fields are height, temperature or pressure maps. In a two-dimensional field, the value at each point can be thought of as a height of a surface embedded in three dimensions. The line integral of a curve along this scalar field is equivalent to the area under a curve traced over the surface defined by the field.

In this animation, all these processes are represented step-by-step, directly linking the concept of the line integral over a scalar field to the representation of integrals familiar to students, as the area under a simpler curve. A breakdown of the steps:

1. The color-coded scalar field f and a curve C are shown. The curve C starts at a and ends at b
2. The field is rotated in 3D to illustrate how the scalar field describes a surface. The curve C, in blue, is now shown along this surface. This shows how at each point in the curve, a scalar value (the height) can be associated.
3. The curve is projected onto the plane XY (in gray), giving us the red curve, which is exactly the curve C as seen from above in the beginning. This is red curve is the curve in which the line integral is performed. The distances from the projected curve (red) to the curve along the surface (blue) describes a "curtain" surface (in blue).
4. The graph is rotated to face the curve from a better angle
5. The projected curve is rectified (made straight), and the same transformation follows on the blue curve, along the surface. This shows how the line integral is applied to the arc length of the given curve
6. The graph is rotated so we view the blue surface defined by both curves face on
7. This final view illustrates the line integral as the familiar integral of a function, whose value is the "signed area" between the X axis (the red curve, now a straight line) and the blue curve (which gives the value of the scalar field at each point). Thus, we conclude that the two integrals are the same, illustrating the concept of a line integral on a scalar field in an intuitive way.