(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A parallel plate capacitor is made of two flat horizontal conducting plates in a vacuum, each of area A, separated by a small gap. One plate carries a total charge 2Q, the other a total charge −Q. Find the surface charge densities on the four horizontal metal surfaces in terms of Q and A. Find the electric field between the plates, and the electric field immediately above and below the capacitor.

2. Relevant equations

3. The attempt at a solution

I would have though ##\sigma_1 =\sigma_2=\frac{Q}{A}## and ##\sigma_3=\sigma_4=-\frac{Q}{2A}## but the answer is ## sigma_1=\frac{Q}{2A}## ##\sigma_2=\frac{3Q}{2A}## ##\sigma_3=\frac{-3Q}{2A}## ##\sigma_4=\frac{-Q}{2A}## but i cannot see how they have got this

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# Homework Help: Charge density of capacitor plates

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