Use the divergence theorem to calculate the flux of a vector field.
Apply the divergence theorem to an electrostatic field.
We have examined several versions of the Fundamental Theorem of Calculus in higher dimensions that relate the integral around an oriented boundary of a domain to a “derivative” of that entity on the oriented domain. In this section, we state the divergence theorem, which is the final theorem of this type that we will study. The divergence theorem has many uses in physics; in particular, the divergence theorem is used in the field of partial differential equations to derive equations modeling heat flow and conservation of mass. We use the theorem to calculate flux integrals and apply it to electrostatic fields.
Overview of theorems
Before examining the divergence theorem, it is helpful to begin with an overview of the versions of the
Fundamental Theorem of Calculus we have discussed:
The Fundamental Theorem of Calculus :
This theorem relates the integral of derivative
over line segment
along the
x -axis to a difference of
evaluated on the boundary.
The Fundamental Theorem for Line Integrals :
where
is the initial point of
C and
is the terminal point of
C . The
Fundamental Theorem for Line Integrals allows path
C to be a path in a plane or in space, not just a line segment on the
x -axis. If we think of the gradient as a derivative, then this theorem relates an integral of derivative
over path
C to a difference of
evaluated on the boundary of
C .
Green’s theorem, circulation form :
Since
and curl is a derivative of sorts,
Green’s theorem relates the integral of derivative curl
F over planar region
D to an integral of
F over the boundary of
D .
Green’s theorem, flux form :
Since
and divergence is a derivative of sorts, the flux form of Green’s theorem relates the integral of derivative div
F over planar region
D to an integral of
F over the boundary of
D .
Stokes’ theorem :
If we think of the curl as a derivative of sorts, then
Stokes’ theorem relates the integral of derivative curl
F over surface
S (not necessarily planar) to an integral of
F over the boundary of
S .
Stating the divergence theorem
The divergence theorem follows the general pattern of these other theorems. If we think of divergence as a derivative of sorts, then the
divergence theorem relates a triple integral of derivative div
F over a solid to a flux integral of
F over the boundary of the solid. More specifically, the divergence theorem relates a flux integral of vector field
F over a closed surface
S to a triple integral of the divergence of
F over the solid enclosed by
S .
The divergence theorem
Let
S be a piecewise, smooth closed surface that encloses solid
E in space. Assume that
S is oriented outward, and let
F be a vector field with continuous partial derivatives on an open region containing
E (
[link] ). Then
Step 1: Find the mean. To find the mean, add up all the scores, then divide them by the number of scores. ...
Step 2: Find each score's deviation from the mean. ...
Step 3: Square each deviation from the mean. ...
Step 4: Find the sum of squares. ...
Step 5: Divide the sum of squares by n – 1 or N.
The sample of 16 students is taken. The average age in the sample was 22 years with astandard deviation of 6 years. Construct a 95% confidence interval for the age of the population.
Bhartdarshan' is an internet-based travel agency wherein customer can see videos of the cities they plant to visit. The number of hits daily is a normally distributed random variable with a mean of 10,000 and a standard deviation of 2,400
a. what is the probability of getting more than 12,000 hits?
b. what is the probability of getting fewer than 9,000 hits?
Bhartdarshan'is an internet-based travel agency wherein customer can see videos of the cities they plan to visit. The number of hits daily is a normally distributed random variable with a mean of 10,000 and a standard deviation of 2,400.
a. What is the probability of getting more than 12,000 hits