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Vector Calculus in Maths

Last Updated : 06 Aug, 2024
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Vector Calculus in maths is a sub-division of Calculus that deals with the differentiation and integration of Vector Functions. We already know that Calculus is a branch of mathematics that deals with the rate of change of a function concerning another function. There are two major divisions of Calculus namely, Differential Calculus and Integral Calculus.

The branch of Differential Calculus deals with the process of finding derivatives or differentiation of functions while Integral Calculus deals with finding the antiderivative of a function whose derivative is given. In this article, we will learn in detail about Vector Calculus which is a lesser-known branch of calculus, and the basic formulas of Vector Calculus.

In this article, you are going to read everything about what is vector calculus in engineering mathematics, vector calculus formulas, vector analysis, etc.

Vector-Calculus

What is Vector Calculus?

Vector Calculus is a branch of mathematics that deals with the operations of calculus i.e. differentiation and integration of vector field usually in a 3 Dimensional physical space also called Euclidean Space. The applicability of Vector calculus is extended to partial differentiation and multiple integration. Vector Field refers to a point in space that has magnitude and direction. These Vector Fields are nothing but Vector Functions. Vector calculus is also known as vector analysis.

The vector fields are the vector functions whose domain and range are not dimensionally related to each other. The branch of Vector Calculus corresponds to the multivariable calculus which deals with partial differentiation and multiple integration. This differentiation and integration of vector is done for a quantity in 3D physical space represented as R3. For n-dimensional space, it is represented as Rn.

Read in Detail: Calculus in Maths

Vector Calculus Definition

Vector calculus, also known as vector analysis or vector differential calculus, is a branch of mathematics that deals with vector fields and the differentiation and integration of vector functions

Vector Calculus often called Vector Analysis deals with vector quantities i.e. the quantities that have both magnitude as well as direction. Since we know that Vector Calculus deals with differentiation and integration of functions, there are three types of integrals dealt with in Vector Calculus that are 

  • Line Integral
  • Surface Integral
  • Volume Integral

Let's learn about these integrals in detail.

Line Integral

Line Integral in mathematics is the integration of a function along the line of the curve. The function can be a scalar or vector whose line integral is given by summing up the values of the field at all points on a curve weighted by some scalar function on the curve. Line Integral is also called Path Integral and is represented by Φ = ∫Lf. Line Integral has got its application in physics. For Example, Work Done by Force is along a path given as W = ∫LF(s).ds because we know that work done is given as the product of force and distance covered.

Surface Integral

Surface Integral in mathematics is the integration of a function along the whole region or space that is not flat. In Surface integral, the surfaces are assumed of small points hence, the integration is given by summing up all the small points present on the surface. The surface integral is equivalent to the double integration of a line integral. Surface Integral has got its application in Electromagnetism and many more branches of physics where the vector function is spread over the surface. Surface Integral is represented as ∬sf(x,y)dA.

Learn more about Double Integral.

Volume Integral

A volume integral, also known as a triple integral, is a mathematical concept used in calculus and vector calculus to calculate the volume of a three-dimensional region within a space. It is an extension of the concept of a definite integral in one dimension to three dimensions.

Mathematically, the volume integral of a scalar function f(x, y, z) over a region R in three-dimensional space is denoted as:

\bold{\iiint_R f(x, y, z) \ dV}

Where 

  • dV represents an infinitesimal volume element, and 
  • Integral is taken over region R.

Operation in Vector

The different operations performed with vector quantities are tabulated below with their notation and illustration.

OperationNotationIllustration

Vector Addition

r1 + r2

Addition of two vectors gives a vector

Scalar Multiplication

q.r1

Multiplying a vector 'r1' with scalar 'q' result in a vector

Dot Product

r1 · r2

Dot product of two vectors gives a scalar

Cross Product

r1 ⨯ r2

Cross product of two vectors gives a vector

Scalar Triple Product

r1 · (r2 ⨯ r3)

Dot Product of Cross product of two vectors

Vector Triple Product

r1 ⨯ (r2 ⨯ r3)

Cross Product of Cross Product of two Vectors

Learn More, Dot and Cross Product of Vectors

Divergence and Curl

Divergence and Curl are two important operators used in Vector Calculus. Divergence is a scalar operator which tells about the behaviour of a function towards or away from a point. Curl is a vector operator which tells about the behaviour of a function around a point. The vector operator is represented by ∇ which accounts for the partial differentiation of the vector field. The Vector Differential Operator (∇) also called Nabla is expressed as ∇ = ∂/∂x i + ∂/∂y j + ∂/∂z k.

Divergence of Vector

If a vector field is given by f(x,y,z) = fxi + fyj + fzk then its divergence is given by taking the scalar of the vector operator is given by

div(f) = ∇.f(x,y,z) = (∂/∂x i + ∂/∂y j + ∂/∂z k) · (fxi + fyj + fzk )

⇒ ∇.f(x,y,z) = ∂x/∂x + ∂y/∂y + ∂z/∂z.

Curl of Vector

If a vector field is given by f(x,y,z) = fxi + fyj + fzk then its curl is given by taking the vector of the vector operator

∇ × f(x,y,z) = (∂/∂x i + ∂/∂y j + ∂/∂z k) ⨯ (fxi + fyj + fzk )

⇒ ∇ × f(x,y,z) = \begin{vmatrix} i & j & k \\ \partial /\partial x& \partial /\partial y & \partial /\partial z \\ f_{x} & f_{y} & f_{z} \\ \end{vmatrix}

⇒ ∇ × f(x,y,z) = (∂z/∂y - ∂y/∂z)i + (∂x/∂z - ∂z/∂x)j + (∂y/∂x - ∂x/∂y).

Gradient of Scalar

The gradient of a scalar field F is given by grad(F) or ∇ F. It gives the measurement of the rate and direction of a scalar-valued function. In the Cartesian system, the gradient of a scalar-valued function is given by

∇ F = (∂/∂x i + ∂/∂y j + ∂/∂z k)F = ∂/∂x i + ∂/∂y j + ∂/∂z k

Vector Calculus Formulas

For a vector field given as F(x,y,z) = p(x,y,z)i + q(x,y,z)j + r(x,y,z)k. The following formulas are given.

Fundamental Theorem of Line Integral

if F = ∇Φ and Curve C has A and B endpoints then its line integral is given as

∫cF.dr = Φ(B) - Φ(A)

Circulation Curl Form

There are two theorems under Circulation Curl Form, namely the Green theorem and Stokes theorem.

Green Theorem: If D is the region bounded by curve C then, ∮cF.dr = ∬D(∂Q/∂x - ∂P/∂y)dA

Stoke's Theorem: For a surface S bounded by curve C stokes theorem given by ∮cF.dr = ∬S(∇ ⨯ F)dS

Flux Divergence Theorem

The Flux Divergence Form of Green's Theorem is given as ∬D∇. F dA = ∮cF.n ds

The Flux Divergence Form of Stoke's Theorem is given as ∭D ∇. F dV = ∯sF.n dσ

Vector Calculus Identities

The list of Vector Calculus Identities have been tabulated under three categories.

Gradient Function Identities

The Gradient Function Identities are tabulated below:

\vec{\nabla}     (f + g)

\vec{\nabla}     f + \vec{\nabla}     g

\vec{\nabla}     (cf)

c\vec{\nabla}     f, where C is constant

\vec{\nabla}     (fg)

f\vec{\nabla}     g + g\vec{\nabla}     f

\vec{\nabla}     (f/g)

(g\vec{\nabla}     f - f\vec{\nabla}g     )/g2 at point \vec{x}     where g(\vec{x}     ) ≠ 0

\vec{\nabla}(\vec{F}+\vec{G})

\vec{F} \times(\vec{\nabla} \times \vec{G})-(\vec{\nabla} \times \vec{F}) \times \vec{G}+(\vec{G} \cdot \vec{\nabla}) \vec{F}+(\vec{F} \cdot \vec{\nabla}

Divergence Function Identities

The identity formula for Divergence Function is tabulated below:

\vec{\nabla}(\vec{F}+\vec{G})

\vec{\nabla} \cdot \vec{F}+\vec{\nabla} \cdot \vec{G}

\vec{\nabla} \cdot(c \vec{F})

c \vec{\nabla} \cdot \vec{F}

\vec{\nabla} \cdot(f \vec{F})

f \vec{\nabla} \cdot \vec{F}+\vec{F} \cdot \vec{\nabla}

\vec{\nabla} \cdot(\vec{F} \times \vec{G})

\vec{G} \cdot(\nabla \times \vec{F})-\vec{F} \cdot(\nabla \times \vec{G})

Curl Function Identities

The identities for curl function is tabulated below:

\vec{\nabla} \times(\vec{F}+\vec{G})

\nabla \times \vec{F}+\vec{\nabla} \times \vec{G}

\vec{\nabla} \times(c \vec{F})

c \vec{\nabla} \times \vec{F}

\vec{\nabla} \times(f \vec{F})

f \vec{\nabla} \times \vec{F}+\vec{\nabla} f \times \vec{F}

\vec{\nabla} \times(\vec{F} \times \vec{G})

\vec{F} \cdot(\vec{\nabla} \cdot \vec{G})-(\vec{\nabla} \vec{F}) \vec{G}+(\vec{G} \cdot \vec{\nabla}) \vec{F}-(\vec{F} \cdot \vec{\nabla})

Laplacian Function Identities

The identities for Laplacian Function is tabulated below:

\vec{\nabla}^2(f+g)

\vec{\nabla}^2 f+\vec{\nabla}^2 g

\vec{\nabla}^2(c f)

c \vec{\nabla}^2 f     , where C is a constant

\vec{\nabla}^2(f g)

f \vec{\nabla}^2 g+2 \vec{\nabla} f \cdot g+g \vec{\nabla}^2

Degree Two Function Identities

The vector calculus identities for two degree function is tabulated below:

\vec{\nabla} \cdot(\nabla \times \vec{F})

0

\vec{\nabla} \times(\vec{\nabla} f)

0

\vec{\nabla} \cdot(\overrightarrow{\nabla f} \times \overrightarrow{\nabla g})

0

\vec{\nabla} \cdot(f \overrightarrow{\nabla g}-g \vec{\nabla})

f \vec{\nabla}^2 g-g \vec{\nabla}^2 f

\vec{\nabla} \times(\nabla \times \vec{F})

\vec{\nabla}(\vec{\nabla} \cdot \vec{F})-\vec{\nabla}^2

Vector Calculus Applications

Vector Calculus or vector analysis has a number of applications in the real world:

Related Resources,

Solved Examples on Vector Calculus

Example 1: If F(x,y,z) = 3xy2 - y2z3 then find gradF or ∇ f.

Solution:

∇ f = (∂/∂x i + ∂/∂y j + ∂/∂z k)(3xy2 - y2z3)

⇒ ∇ f = ∂/∂x(3xy2 - y2z3)i + ∂/∂y(3xy2 - y2z3)j + ∂/∂z (3xy2 - y2z3)k

⇒ ∇ f = 3y2i + (6xy - 2yz3) + (-3y2z2)k

Example 2: Find the div(F) or ∇·F, if F = xz2 i - 2y2z3 j + x2yz k

Solution:

div(F) = ∇·F = (∂/∂x i + ∂/∂y j + ∂/∂z k)·(xz2 i - 2y2z3 j + x2yz k)

⇒ ∇·F = ∂/∂x(xz2) + ∂/∂y(- 2y2z3) + ∂/∂z(x2yz)

⇒ ∇·F = z2 - 4yz3 + x2y

Example 3: Find curl F i.e. ∇ × f if F = xz2 i - 2x3yz j + 2yz4 k

Solution:

∇ × f= (∂/∂x i + ∂/∂y j + ∂/∂z k) ⨯ (xz2 i - 2x3yz j + 2yz4 k)

⇒ ∇ × f = \begin{vmatrix} i & j & k \\ \partial /\partial x& \partial /\partial y & \partial /\partial z \\ xz^{2} & 2x^{3}yz & 2yz^{4} \\ \end{vmatrix}

⇒ ∇ × f = [∂/∂y(2yz4) - ∂/∂z(-2x3yz)]i + [∂/∂z(xz2) - ∂/∂x(2yz4)]j + [∂/∂x(-2x3yz) - ∂/∂y(xz2)]k

⇒ ∇ × f = [2z4 + 2x3y]i + [2xz - 0]j + [-6x2yz - 0]k

⇒ ∇ × f = (2z4 + 2x3y)i + (2xz)j -(6x2yz)k

Solved Examples

1. Calculate the gradient of f(x,y,z) = x^2y + yz^3 + xz

Solution:

∇f = (∂f/∂x, ∂f/∂y, ∂f/∂z)

∂f/∂x = 2xy + z

∂f/∂y = x^2 + z^3

∂f/∂z = 3yz^2 + x

∇f = (2xy + z, x^2 + z^3, 3yz^2 + x)

2. Find the divergence of F(x,y,z) = (x^2 + y)i + (y^2 + z)j + (z^2 + x)k

Solution:

div F = ∇ · F = ∂F_x/∂x + ∂F_y/∂y + ∂F_z/∂z

∂F_x/∂x = 2x

∂F_y/∂y = 2y

∂F_z/∂z = 2z

div F = 2x + 2y + 2z

3. Calculate the curl of F(x,y,z) = (yz)i + (xz)j + (xy)k

Solution:

curl F = ∇ × F = (∂F_z/∂y - ∂F_y/∂z)i + (∂F_x/∂z - ∂F_z/∂x)j + (∂F_y/∂x - ∂F_x/∂y)k

∂F_z/∂y - ∂F_y/∂z = x - x = 0

∂F_x/∂z - ∂F_z/∂x = y - y = 0

∂F_y/∂x - ∂F_x/∂y = z - z = 0

curl F = 0i + 0j + 0k = 0

4. Evaluate ∫_C (x^2 + y^2) ds, where C is the circle x^2 + y^2 = 1, traversed counterclockwise.

Solution:

Parameterize the circle: x = cos(t), y = sin(t), 0 ≤ t ≤ 2π

ds = √((dx/dt)^2 + (dy/dt)^2) dt = √(sin^2(t) + cos^2(t)) dt = dt

∫_C (x^2 + y^2) ds = ∫_0^(2π) (cos^2(t) + sin^2(t)) dt = ∫_0^(2π) 1 dt = 2π

5. Compute the flux of F(x,y,z) = xi + yj + zk through the surface of the sphere x^2 + y^2 + z^2 = a^2.

Solution:

Use the divergence theorem: ∫∫_S F · dS = ∫∫∫_V div F dV

div F = 1 + 1 + 1 = 3

Volume of sphere = (4/3)Ï€a^3

Flux = ∫∫∫_V 3 dV = 3 * (4/3)πa^3 = 4πa^3

Practice Problems on Vector Calculus in Maths

1. Calculate the gradient of f(x,y,z) = ln(x2 + y2 + z2)

2. Find the divergence of F(x,y,z) = (x2y)i + (y2z)j + (z2x)k

3. Compute the curl of F(x,y,z) = (y2)i + (z2)j + (x2)k

4. .Evaluate the line integral ∫_C (x + y) ds along the curve C: x = t, y = t2, z = t3, 0 ≤ t ≤ 1

5. Calculate the surface integral of F(x,y,z) = xi + yj + zk over the surface z = x2 + y2, 0 ≤ z ≤ 1

6. Find the gradient of f(x,y) = e(x+y) sin(xy)

7. Determine if F(x,y,z) = (yz)i + (zx)j + (xy)k is conservative

8. Compute the divergence of F(r,θ,φ) = r^ cos(φ)r + r sin(θ) sin(φ)θ + r cos(θ)φ in spherical coordinates

9. Find the potential function for F(x,y) = (2x + y)i + (x + 2y)j

10. Calculate the work done by F(x,y,z) = xi + yj + zk along the helix r(t) = (cos(t), sin(t), t), 0 ≤ t ≤ 2π

Summary

Vector calculus is a branch of mathematics that deals with vector fields in two or more dimensions. It encompasses key concepts such as the gradient, which measures the rate and direction of change in scalar fields; divergence, which quantifies the "outflow" of vector fields; and curl, which describes the rotation of vector fields. The field also includes techniques for integration over curves (line integrals) and surfaces (surface integrals). Fundamental theorems like the Divergence Theorem and Stokes' Theorem connect these concepts, while the study of conservative fields and potential functions provides insights into path independence and field representations. These tools and concepts are essential for analyzing complex systems in physics, engineering, and other scientific disciplines, allowing for the mathematical description of phenomena involving fluid dynamics, electromagnetism, and other multidimensional processes.


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