Boundary Conditions in Dielectrics and Magnetics

Which of the following boundary conditions must be satisfied by the tangential component of the electric field at the interface between two dielectric materials?

• It must be continuous.

• It must be zero.

• It must be perpendicular to the surface.

The normal component of the electric flux density (Dn​) at the boundary between two dielectric materials changes according to:

• The ratio of permeabilities

• The ratio of permittivities

• The surface charge density at the boundary

If there is no surface charge density at the boundary between two dielectric materials, what happens to the normal component of the electric flux density (Dn​)?

• It becomes discontinuous.

• It remains continuous.

• It is always zero.

The boundary condition for the tangential component of the magnetic field (Ht​) states that it is discontinuous when:

• There is a surface current at the boundary

• The materials have different conductivities

• The permeability of one medium is very high

The normal component of the magnetic flux density (Bn​) at the boundary between two magnetic materials is:

• Continuous

• Discontinuous if the permeability changes

• Always equal to the surface current

Which of the following best describes the boundary condition for the electric field at the surface of a perfect conductor?

• The electric field is always parallel to the surface.

• The electric field is always perpendicular to the surface.

• The tangential component of the electric field is nonzero.

If there is no surface current at the interface between two magnetic materials, how does the tangential component of the magnetic field behave across the boundary?

• It is zero.

• It is continuous.

• It depends on the dielectric permittivity.