A small sphere whose mass m is 1.0 x 10 -3 g, carries a charge q of 2.0 x 10 -8 C. It hangs from a silk thread which makes an angle of 30 with a large, charged conducting sheet as show.

Calculate the surface charge density (sigma) for the sheet.

Question

A small sphere whose mass m is 1.0 x 10 -3 g, carries a charge q of 2.0 x 10 -8 C. It hangs from a silk thread which makes an angle of 30 with a large, charged conducting sheet as show.

Calculate the surface charge density (sigma) for the sheet.

anonymous · Answer

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anonymous · Answer

So far, using the "PillBox" Gaussian Surface, I found that 
$$\sigma=E2\epsilon_0$$

anonymous · Answer

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anonymous · Answer

from the graph above, i get that $$E=mgtan \theta + q$$

anonymous · Answer

Now I plugin E and solve for (sigma). I just want to know if I'm doing this right

anonymous · Answer

@dan815 @radar @Compassionate Anyone have an idea? Your help will be greatly appreciated :)

anonymous · Answer

Is that just a typo in your equation for E ?
It should be E=mgtan(theta)/q
Other than that your method looks fine.