BEE Engineering Electromagnetics Fundamentals 4

Question 1

The electric flux density D and electric field E in a linear isotropic dielectric are related by:

Accepted Answer

D = ε₀εᵣE

Answer

In a linear isotropic medium, D = ε₀εᵣE = εE, where εᵣ is the relative permittivity.

Question 2

The magnetic vector potential A is defined such that:

Accepted Answer

B = ∇×A

Answer

The magnetic flux density is defined as B = ∇×A, automatically satisfying ∇·B = 0.

Question 3

Standing waves on a transmission line occur when:

Accepted Answer

The load is mismatched (Γ ≠ 0)

Answer

A mismatched load causes a reflected wave; the incident and reflected waves superpose to form standing waves.

Question 4

The electric field intensity E is related to the scalar potential V and vector potential A by:

Accepted Answer

E = -∇V - ∂A/∂t

Answer

In the general time-varying case, E = -∇V - ∂A/∂t, reducing to E = -∇V in electrostatics.

Question 5

The condition for total internal reflection at a dielectric interface is that the angle of incidence θᵢ satisfies:

Accepted Answer

θᵢ > θ_c where sin θ_c = n₂/n₁ (n₁ > n₂)

Answer

Total internal reflection occurs when θᵢ exceeds the critical angle θ_c = arcsin(n₂/n₁) for n₁ > n₂.

BEE - Bachelor of Electrical Engineering Practice Test