Question

When the electric field direction is opposite to the area vector (θ = 180°), what is the flux?

Options

• \[\Phi = 0\]

• \[\Phi = -EA\]

• \[\Phi = EA/2\]

• \[\Phi = EA\]

Answer 1

When θ = 180°, \[\cos(180°) = -1\], so \[\Phi = EA \cos(180°) = -EA\]. This represents the maximum negative flux, indicating that field lines enter the surface opposite to the direction of the chosen outward normal.