- #1

- 343

- 11

..where can be found:

What in the whole wide world does Zee mean with

??

Thank you

What in the whole wide world does Zee mean with

Thank you

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- A
- Thread starter Lapidus
- Start date

- #1

- 343

- 11

..where can be found:

What in the whole wide world does Zee mean with

??

Thank you

What in the whole wide world does Zee mean with

Thank you

- #2

DrDu

Science Advisor

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- #3

- 343

- 11

But on what else could the partial derivative act on than on A?

- #4

DrDu

Science Advisor

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- 886

- #5

mfb

Mentor

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A better way to write this would be

$$(\partial_i A_i + A_i \partial_i) X = (\partial_i A_i)X + 2 A_i \partial_i X = 2 A_i \partial_i X$$

for some wave function X and ignoring indices there. Just the product rule applied to ##\partial_i A_i X##

Edit: Added missing X

$$(\partial_i A_i + A_i \partial_i) X = (\partial_i A_i)X + 2 A_i \partial_i X = 2 A_i \partial_i X$$

for some wave function X and ignoring indices there. Just the product rule applied to ##\partial_i A_i X##

Edit: Added missing X

Last edited:

- #6

- 343

- 11

Got it! Thanks DrDu and mfb!

- #7

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- #8

ChrisVer

Gold Member

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Although I think similar expressions were in Griffith's Intro to Electrodynamics.

(feels like Zee's advocate)

- #9

nrqed

Science Advisor

Homework Helper

Gold Member

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Just to point out a small misprint (mfb just forgot): there is an X missing in the middle expression$$(\partial_i A_i + A_i \partial_i) X = (\partial_i A_i) X + 2 A_i \partial_i X = 2 A_i \partial_i X$$A better way to write this would be

$$(\partial_i A_i + A_i \partial_i) X = (\partial_i A_i) + 2 A_i \partial_i X = 2 A_i \partial_i X$$

for some wave function X and ignoring indices there. Just the product rule applied to ##\partial_i A_i X##

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