Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of the same sign and of magnitude 17.7×10⁻²² C/m². What is E in the outer region of the second plate?

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(2) 2×10⁻¹⁰ N C⁻¹. Given: σ=17.7×10⁻²² C/m² on each inner face, both of the same sign; ε₀=8.85×10⁻¹² C² N⁻¹ m⁻². Idea: treat each charged face as a large sheet, which gives σ/(2ε₀) on either side, directed away from it (for positive σ). Beyond the second plate both fields point the same way, away from the pair, so they add: E=σ/(2ε₀)+σ/(2ε₀)=σ/(ε₀) E=(17.7×10⁻²²)/(8.85×10⁻¹²)=2×10⁻¹⁰ N C⁻¹ (Between the plates the two fields point in opposite directions and cancel.)

Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of the same sign and of magnitude 17.7×10⁻²² C/m². What is E in the outer region of the second plate?

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