Vector field in cylindrical coordinates

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Les talons
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Homework Statement


Sketch each of the following vector fields.
[itex]E_5 = \hat \phi r[/itex]
[itex]E_6 = \hat r \sin(\phi)[/itex]

I wish to determine the [itex]\hat x[/itex] and [itex]\hat y[/itex] components for the vector fields so that I can plot them using the quiver function in MATLAB.

Homework Equations


A cylindrical coordinate is given by [itex](r, \phi, z)[/itex]
[itex]r = \sqrt[+]{x^2 + y^2}[/itex]
[itex]\phi = \arctan(y/x)[/itex]
[itex]z = z[/itex]
Transformation from cylindrical coordinates into Cartesian coordinates:
[itex]\hat x = \hat r \cos(\phi) - \hat \phi \sin(\phi)[/itex]
[itex]\hat y = \hat r \sin(\phi) + \hat \phi \cos(\phi)[/itex]

The Attempt at a Solution


[itex]E_5 = \hat \phi r[/itex]
Since the given vector field [itex]E_5[/itex] only has a [itex]\hat \phi[/itex] component,
[itex]\hat x = \hat r \cos(\phi) - \hat \phi \sin(\phi) = 0 \cos(\phi) - r \sin(\phi) = - \sqrt[+]{x^2 + y^2} \sin(\phi)[/itex]
Then I transformed [itex]\phi[/itex] in terms of [itex]x[/itex] and [itex]y[/itex] based on the definition of a cylindrical coordinate
[itex]\hat x = - \sqrt{x^2 + y^2} \sin(\arctan(y/x)) = \displaystyle \frac{-y \sqrt{x^2 + y^2} }{x \sqrt{1 +y^2 /x^2} }[/itex]
I followed the same approach for the [itex]\hat y[/itex] component
[itex]\hat y = \hat r \sin(\phi) + \hat \phi \cos(\phi) = 0 \sin(\phi) + r \cos(\phi) = \sqrt[+]{x^2 + y^2} \cos(\phi)[/itex]
[itex]\hat y = \sqrt{x^2 + y^2} \cos(\arctan(y/x)) = \displaystyle \frac{\sqrt{x^2 + y^2} }{\sqrt{1 +y^2 /x^2} }[/itex]
Then
[itex]E_5 = - \hat x \displaystyle \frac{y \sqrt{x^2 + y^2} }{x \sqrt{1 +y^2 /x^2} } + \hat y \displaystyle \frac{\sqrt{x^2 + y^2} }{\sqrt{1 +y^2 /x^2} }[/itex]

Is this approach valid? Thanks for helping. I'll post my attempt for [itex]E_6[/itex] in a little while.

I'm having trouble thinking about the vector field since I'm used to working in Cartesian coordinates, so I can't tell if this makes sense.
 
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[itex]E_6 = \hat r \sin(\phi)[/itex]
[itex]\hat x = \sin(\phi) \cos(\phi) = \sin(\arctan(y/x)) \cos(\arctan(y/x))[/itex]
[itex]\hat y = \sin^2(\phi) = \sin^2(\arctan(y/x))[/itex]
 
If anyone happens upon this thread looking for help in a similar question, the correct conversions are as follows for the [itex]\hat x[/itex] and [itex]\hat y[/itex] components of [itex]\vec E_5[/itex]:
[itex]E_{5x} = E_{5r} \cos \phi - E_{5\phi} \sin \phi[/itex]
[itex]E_{5y} = E_{5r} \sin \phi + E_{5\phi} \cos \phi[/itex]

and similarly for [itex]\vec E_6[/itex] (or another vector in cylindrical coordinates)