Boundary Conditions
Boundary Conditions
The section discusses the behavior of waves at the boundary between two different materials.
Tangential Electric Field
- The tangential electric field has to be the same on the boundary.
- The tangential flux changes, but the tangential electric field remains constant.
Normal Component of Electric Field
- The normal component of the electric flux density vector D stays the same if there is no charge at the boundary.
- Epsilon 1 E1 has to be equal to epsilon 2 P2.
Generalized Form of Ohm's Law
This section introduces a generalized form of Ohm's law and discusses its application in understanding boundaries between metals and dielectrics.
Generalized Form of Ohm's Law
- Current density is proportional to conductance times electric field.
- In metals, electric field is zero because Sigma is infinite.
Boundaries Between Metals and Dielectrics
- The tangential electric field at the surface of a metal must be zero.
- There may be surface charge density on a metal, which affects D2n.
- On the surface of a metal, the electric field must be perpendicular to it if it exists.
Sketching Electric Fields Around Metal Spheres
This section explains how to sketch an electric field around a metal sphere.
Sketching Electric Fields Around Metal Spheres
- Inside a metal sphere, there can be no electric fields.
- Outside a metal sphere, the electric field will bend and go into a 90-degree angle to the metal, and there will be a charge separation.