Engineering Electromagnetics Fundamentals Flashcards

The magnetization M of a magnetic material is related to the magnetic susceptibility χ_m and H by:

Answer: M = χ_m H

By definition, M = χ_m H, where χ_m is dimensionless and positive for paramagnetic materials.

In the method of images, a point charge +Q placed at height h above an infinite grounded conducting plane is equivalent to:

Answer: -Q at height -h (below the plane)

The image charge is -Q placed at distance h on the opposite side of the grounded plane to enforce V = 0 on the surface.

Ampere's law with Maxwell's displacement current correction in integral form is:

Answer: ∮H·dl = I_enc + ∬(∂D/∂t)·dS

Maxwell added the displacement current ∂D/∂t to Ampere's law: ∮H·dl = I_enc + ∬(∂D/∂t)·dS.

The critical angle for total internal reflection when light passes from glass (n=1.5) to air (n=1.0) is approximately:

Answer: 41.8°

θ_c = arcsin(1.0/1.5) = arcsin(0.667) ≈ 41.8°, the minimum angle for total internal reflection.

The torque T experienced by a magnetic dipole m in a uniform magnetic field B is:

Answer: T = m × B

The torque is T = m × B, tending to align the magnetic moment with the applied field.

The power dissipated per unit volume in a conducting medium with conductivity σ and electric field E is:

Answer: P = σE²

Ohmic power loss per unit volume is P = J·E = σE·E = σE², known as Joule heating.

Which parameter determines the ratio of conduction current to displacement current in a material at angular frequency ω?

Answer: Loss tangent tan δ = σ/(ωε)

The loss tangent tan δ = σ/(ωε) = J_c/J_d is the ratio of conduction to displacement current density magnitude.