- #1
Sparky_
- 227
- 5
I am working through chapter 10 of Griffith’s electrodynamics (for fun and in my spare time). While I don’t have a formal bucket list, getting to an understanding of how Newton’s third law is not as straightforward for electrodynamics has been on my mental bucket list.
I am an engineer not a physicist. I find myself having to research and review a good bit especially on the mathematics.
On page 436, Griffith is showing the differentiation and simplification of
[tex] \nabla V [/tex] (pg. 435)
Through some product rules and algebra and so forth he is simplifying terms.
On the bottom of page 436 he has:
[tex] \nabla \times \mathcal r = \nabla \times \mathtt r- \nabla \times w [/tex]
(X = cross product)
W = position function for moving charge
Script r = r – w
[tex] \mathcal r = \mathtt r- w [/tex]
r = position vector
My question is in the text, the author has the statement:
[tex] \nabla \times \mathtt r = 0 [/tex]
No reason, no background just the statement. So I assume I am supposed to know this and it is probably obvious but I don’t see it.
I wrote out the cross product for del x r in matrix form and turned the crank – nothing canceled or became apparent.
Can you explain why
[tex] \nabla \times \mathtt r = 0 [/tex]
Del cross position vector is zero?
Thanks
Sparky_
I am an engineer not a physicist. I find myself having to research and review a good bit especially on the mathematics.
On page 436, Griffith is showing the differentiation and simplification of
[tex] \nabla V [/tex] (pg. 435)
Through some product rules and algebra and so forth he is simplifying terms.
On the bottom of page 436 he has:
[tex] \nabla \times \mathcal r = \nabla \times \mathtt r- \nabla \times w [/tex]
(X = cross product)
W = position function for moving charge
Script r = r – w
[tex] \mathcal r = \mathtt r- w [/tex]
r = position vector
My question is in the text, the author has the statement:
[tex] \nabla \times \mathtt r = 0 [/tex]
No reason, no background just the statement. So I assume I am supposed to know this and it is probably obvious but I don’t see it.
I wrote out the cross product for del x r in matrix form and turned the crank – nothing canceled or became apparent.
Can you explain why
[tex] \nabla \times \mathtt r = 0 [/tex]
Del cross position vector is zero?
Thanks
Sparky_