In a region of fair weather, the electric feild is found to be vertically down. At an altitude of 400m E=20 N/C at 200m E=90 N/C. Find the net charge contained in a cube 200m on and edge, with horizontal faces at altititudes of 200m and 400m.(adsbygoogle = window.adsbygoogle || []).push({});

I wasn't sure where to start so i used coulumbs law and plugged in the altitudes and electric feilds.

[tex]20=\frac{kQ}{400^2}[/tex] and [tex]90=\frac{kQ}{200^2}[/tex]

Then i found the difference and got .4e6. I thought that would be the answer maybe, but its mult choice and thats not one of them. So now i'm not really sure what to do....

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# Homework Help: Cube in an electric feild

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