Question

Why electric field is normal to surface of conductor?

Answer 1

Reason for normal electric field

• The surface of a conductor is an equi-potential surface. So, potential $V=cons\tan t$.
• We know that electric field is related to potential as $E=-\frac{dV}{dr}\Rightarrow dV=-E.dr$, where $E$ is the electric field and $dr$is the distance between two points on the surface.
• For an equipotential surface, $dV=0\Rightarrow E.dr=0$
• So we can say, $E\perp dr$
• Thus, the electric field is normal to the surface.