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If an enclosed surface has electric flux ϕ₁ entering it and ϕ₂ leaving it, what is the net charge enclosed by the surface?

1. (ϕ₂ − ϕ₁)/ε₀
2. (ϕ₁ + ϕ₂)/ε₀
3. (ϕ₁ − ϕ₂)/ε₀
4. (ϕ₂ + ϕ₁)/ε₀

Correct answer: (ϕ₂ − ϕ₁)/ε₀

Solution

According to Gauss's law, the net electric flux through a closed surface is directly proportional to the net charge enclosed within that surface. The net charge is calculated by subtracting the total flux entering the surface from the total flux leaving it, which is represented by (ϕ₂ − ϕ₁)/ε₀.

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