The field just outside a charged conductor surface with surface charge density σ is:

The field just outside a charged conductor surface with surface charge density σ is:

• A. E_out = σ/ε0 n̂
• B. E_out = σ/ε n̂
• C. E_out = σ E0 n̂
• D. E_out = k σ n̂

Answer: (D)

The field just outside a charged conductor is perpendicular to the surface and its magnitude is set by the surface charge density. Using a tiny pillbox that straddles the surface and Gauss’s law, the field inside the conductor is zero, so the flux comes only from the outer face: E_out A = Q_enc/ε0 = σ A/ε0. This gives E_out = (σ/ε0) n̂, directed outward. If the problem uses a constant k to denote the same proportionality factor in the chosen unit system, then E_out = k σ n̂ expresses the same relation. In SI units, k would correspond to 1/ε0, so this matches the standard result.

The field just outside a charged conductor is perpendicular to the surface and its magnitude is set by the surface charge density. Using a tiny pillbox that straddles the surface and Gauss’s law, the field inside the conductor is zero, so the flux comes only from the outer face: E_out A = Q_enc/ε0 = σ A/ε0. This gives E_out = (σ/ε0) n̂, directed outward.

If the problem uses a constant k to denote the same proportionality factor in the chosen unit system, then E_out = k σ n̂ expresses the same relation. In SI units, k would correspond to 1/ε0, so this matches the standard result.