Green's, Stokes' and Divergence theorems. Flashcards

1
Q

What is Green’s theorem in the plane?

A
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2
Q

How can you write Green’s theorem in the plane in vector form?

A
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3
Q

What is Stokes’ theorem a generalisation of?

A

Green’s theorem to arbitrary surfaces

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4
Q

What is Stoke’s theorem?

A
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5
Q

What is the divergence theorem?

A
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6
Q

What are these three theorems extensions of?

A

The fundamental theorem of calculus.

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7
Q

What is an important application of the divergence theorem?

A

Conservation laws and the continuity equation.

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8
Q

What is an interpretation of the following?

A

The flux of some quantity F through the surface of interest.

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9
Q

What is flux?

A

Flux is the rate of flow per unit area

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10
Q

Which way is flux measured?

A

Perpendicular to the face of the surface

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11
Q

How is flux related to dA?

A

Flux is dA multiplied by the unit normal vector ň

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12
Q

What are fives fluxes?

A
  1. Magnetic flux (F = B)
  2. Electric fluc (F = E)
  3. Transport fluxes such as mass (F = ρv)
  4. Heat
  5. Energy
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13
Q

What is the continuity equation?

A
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14
Q

What is an application of Stoke’s theorem?

A

Path independence of line integrals.

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15
Q

What is a conservative vector field?

A

Vector fields for which the line integral is path independent.

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16
Q

Define simply connected.`

A
17
Q

If D is simply connected what does the imply about path independence?

A
18
Q

If ∇ x F is zero in some region D what does this imply about F?

A

F is the gradient of the scalar field there.

F = ∇ɸ

19
Q

What is the funciton ɸ called?

A

The scalar potential

20
Q

Prove that when you start with F = ∇ɸ you can show path independence directly.

A
21
Q

How does path indepence, ∇ x F = 0 and the scalar potential relate?

A
22
Q

What does j stand for in the following continuity equation?

A

j = ρv, which is the flux

23
Q

If the closed curve is the boundary of a surface S, and if ∇ x F = 0 on S than what is the following equal to?

A

0 - no need to do the surface integral

24
Q

A change in variables is also known as?

A

A change in coordiante system

25
Q

In general what do we require maps from one set of coorindates to another be?

A

Diffeomorphisms - to be differentiable and have differentiable inverses.

26
Q

In two dimensions, how do we change the area element of the integral with a change of variables?

A
27
Q

What is the general change of variables integral formula?

A

For any v and any number of dimensions we have the following:

28
Q

What is the Jacobian for W?

A
29
Q

What is the Jacobian a matrix of?

A

Partial derivatives

30
Q

How can the continuiy equation be represented using the divergence theorem?

A