X and y componants of electric field

[rwooduk]

Homework Statement

Homework Equations

Vectors.

The Attempt at a Solution

I understand the magnitude part, and I'm probably being really stupid here but I can't see how he has got the x and y values for the components (circled in red). If anyone could help it would really be appreciated.

 

[pasmith]

You have \vec E = |E|(\cos \theta\,\vec x + \sin \theta\,\vec y) for some \theta. Given the horizontal dimensions of the sheet, what are \cos \theta and \sin \theta?

To calculate |E|\cos \theta and |E|\sin \theta you should use the exact value of |E|, not the approximation 223.61 kV/m.

 

[rwooduk]

You have \vec E = |E|(\cos \theta\,\vec x + \sin \theta\,\vec y) for some \theta. Given the horizontal dimensions of the sheet, what are \cos \theta and \sin \theta?

To calculate |E|\cos \theta and |E|\sin \theta you should use the exact value of |E|, not the approximation 223.61 kV/m.

Thats very helpful. Thankyou! Although for some reason I get 200 for |E|\cos \theta and 100 for |E|\sin \theta. But I'm happy just to understand the method he used. Thanks!

 

[pasmith]

Thats very helpful. Thankyou! Although for some reason I get 200 for |E|\cos \theta and 100 for |E|\sin \theta. But I'm happy just to understand the method he used. Thanks!

You may have interchanged \vec x and \vec y. Note that in the diagram the longer side of the sheet is parallel to the y-axis, which is horizontal across the page.

 

[rwooduk]

You may have interchanged \vec x and \vec y. Note that in the diagram the longer side of the sheet is parallel to the y-axis, which is horizontal across the page.

Ahhhh, didnt notice the axis. Thank you!