Gradient and Divergence in spherical coordinates

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Homework Help Overview

The discussion revolves around the concepts of gradient and divergence in spherical coordinates, focusing on vector fields and their representations. Participants are examining the mathematical expressions related to these concepts.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants are sharing their expressions for vector fields and questioning the dimensional consistency of the results. There is an exploration of how to derive the gradient and divergence using linear algebra and vector operations.

Discussion Status

The discussion is ongoing, with participants presenting differing results and questioning each other's expressions. Some guidance on deriving the gradient in spherical coordinates has been suggested, but no consensus has been reached regarding the correct forms or interpretations.

Contextual Notes

There are indications of missing information regarding the definitions and assumptions used in the expressions, as well as a note on the use of LaTeX for clarity in mathematical representation.

physicss
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Homework Statement
Hello, are my answers correct?

I had to calculate the gradient of f=z and f=xy in spherical coordinates.
My solution for f= z is: cos(θ) er+ (-sin(θ)) e(θ)

f=xy

rsin^2(θ)sin(2φ) er+ rcos(θ)cos(φ)sin(θ)sin(φ) e(θ)+ rcos(2φ)sin(θ) e(φ)

I also had to calculate the divergence of the following vectorfield (Image)

My result is: (scalarfield)

Sin^2(θ)cos^2(φ) er + rcos(2θ)cos^2(φ) e(θ)-rsin(θ)cos(2φ) e(φ)


Thanks in advance
Relevant Equations
er, e(θ) and e(φ) are the spherical base vectors
9527BE5E-8449-4D24-8FA2-A3BE2FC41DD0.jpeg

Vectorfield for the divergence
 
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physicss said:
rsin^2(θ)sin(2φ) er+ rcos(θ)cos(φ)sin(θ)sin(φ) e(θ)+ rcos(2φ)sin(θ) e(φ)
I get a slightly different ##\vec e_\theta##.
Please learn to use LaTeX.
 
physicss said:
My result is: (scalarfield)

Sin^2(θ)cos^2(φ) er + rcos(2θ)cos^2(φ) e(θ)-rsin(θ)cos(2φ) e(φ)
If it is a scalar, how come it has ##\vec e_r## etc?
I also note a dimensional inconsistency.
 
You can get the gradient in spherical (or any other) coordinates by direct substitution, using basic linear algebra. From there you can get div, curl, and the Laplacian just by vector operations:
 

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